Evolving Clinical Presentation and Assessment of Pheochromocytoma: A Review

Introduction

Pheochromocytoma (PHEO) is a rare adrenomedullary tumor causing secondary hypertension, with an incidence of 0.1-0.6%.(1-5) These tumors can synthesize, metabolize, store, and secrete catecholamines and their metabolites. (6) A high index of clinical suspicion remains the pivotal point to initiate biochemical studies, particularly in those patients with certain patterns of spells, blood pressure elevations (paroxysmal or alternating with hypotension), drug-resistant hypertension, sudden palpitations with or without pallor, unexplained sweating particularly at night or in cold weather, unexplained hyperglycemia, and a hereditary predisposition for PHEO.(7-13)   

Although biochemical testing for PHEO is indicated for symptomatic patients as described above, it is also indicated for patients with incidentally found adrenal lesions or identified genetic predispositions or syndromic presentation pointing towards a high likelihood to develop PHEO (e.g. in patients with multiple endocrine neoplasia type 2 (MEN2), von Hippel-Lindau syndrome (VHL), neurofibromatosis type 1 (NF1), mutations of the succinate dehydrogenase genes (SDHB, SDHD), and hypoxia-induced factor 2A (HIF2A)-related PHEO-polycythemia syndrome).(14-23) Only after PHEO is biochemically proven should imaging be performed. Current imaging modalities include anatomical (CT, MRI) and functional (molecular) imaging procedures using various radiopharmaceuticals, depending on the clinical situation. If a detailed clinical assessment together with well-thought and appropriate diagnostic approaches is not applied, consequences from improper or delayed diagnosis of PHEO almost always occur. This may lead to catastrophic consequences from sudden catecholamine release and their impact on cardiovascular and other systems, including lethal tachyarrhythmia, myocardial infarction, stroke, or death,24 and significant myocardial dysfunction persisting even after normalization of catecholamine levels postoperatively. (25)

During the last few years, enormous progress has been made in the diagnosis of PHEO.  These new discoveries include the inclusion of 3-methoxytyramine in the biochemical diagnosis,26-29 new reference values for seating and standing metanephrine levels, new reference values for children,11 metabolite profiling (metabolomics) and evaluation of relationships between metabotypes and genotypes,30 in vivo proton magnetic spectroscopy for the assessment of catecholamines and succinate, the use of new functional imaging modalities particularly somatostatin analogs radiolabeled with gallium-68 (68Ga-DOTA-SSA) 31 in the localization of PHEO, and finally the advancement in the identification and characterization of new susceptible genes related to disruption of HIF degradation, such as prolyl hydroxylase (PHD) and HIF mutations, 21,32 mutations in chromatin remodeling genes, e.g. MERTK, MET, and H3F3A, (33) and disruption in DNA copy numbers.(34) Also, new therapeutic approaches are on the horizon focusing on HIF-2 inhibitors, hypomethylating agents, and 177Lu-DOTATATE for peptide receptor radionuclide therapy (PRRT) and precision medicine approach. (35)

This review is undertaken to provide insight on the evolving clinicalpresentation of pheochromocytoma and to come up with diagnostic algorithms that will guide clinicians for early identification of the evolving clinical presentation and timely assessment of pheochromocytoma.

 

The Sympathoadrenal (SA) Cell Lineage And The Adrenal Medulla

The SA cells are a sub-lineage of the neural crest, giving rise to neuroendocrine chromaffin cells in the adrenal medulla and extra-adrenal neurons clinically called paraganglia.36 These SA derivatives have the common characteristics to synthesize, store, and release catecholamines. The migration of these cells is found along the sympathetic ganglia from the neck, mediastinum, and abdomen, down to the urinary system. The sympathetic neurons and chromaffin cells share the same progenitor in the neural crest. BMP-4 has shown to be the major induction factor for maturation of SA progenitor cells (Figure 1). (37) The differentiation of the SA cellular lineage to sympathetic neurons and chromaffin cells may be due to inherent environmental influence but remain unclear. However, it is during this phase of NC cells migration in the presence of established transcription factors (TFs) including MASH-1, Phox2a, Phox2b, Hand2, Gata2/3 and Insm1 that they acquire catecholaminergic features and phenotypes. (38-40) Other hypothetical suggested TFs are NOTCH-signaling, HAIRY1/2/3, and DELTA1, SERRATE, and NUMB, Inscuteable/dlg1. (40-41)

The temporal triggering events for specific chromaffin cells remain debatable due to lack of appropriate markers. The final target regions such as the adrenal medulla, paraganglia, and sympathetic ganglia have been demonstrated to be influenced by glucocorticoids (GCs). (42-44) The GC- signaling has shown to not originate specifically from adrenal cortex and even present in GC-deficient mice. Several crosstalk pathways between GC/GR signaling, GR/MAPK pathways, IGF-1, FGF-2, and NGF receptor trkA have been described (45-46) which is vital for chromaffin survival. GC signaling is likewise crucial in the induction of adrenaline synthesizing enzyme phenyl ethanolamine-N-methytransferase (PNMT), so that GC-deficient mice only produce noradrenaline. (46) In GC receptor knockout mice, chromaffin vesicles are intact and can still be identified by molecular markers such as neuropeptides, transporters, and chromogranin B. (47)

 

Catecholamine Synthesis And Metabolism: Physiologic Vs. Pathologic In Pheochromocytoma

The mother substance for catecholamine synthesis is amino acid L-tyrosine. Tyrosine is derived from the diet or synthesized from phenylalanine.  Synthesis starts at the rate-limiting step of conversion of tyrosine 3,4-dihydroxyphenylalanine (DOPA) by the enzyme tyrosine hydroxylase (TH) (Fig. 2A). (48) Conversion of DOPA to dopamine (DA) is catalyzed by aromatic L-amino acid decarboxylase (AADC). The DA formed in the cytoplasm by AADC is transported into vesicular storage granules. In dopaminergic neurons, DA is released without any further conversion to norepinephrine (NE), but in noradrenergic neurons and adrenal chromaffin cells DA is further converted to NE by dopamine b-hydroxylase (DBH). (16,49) The enzyme is present in vesicular storage granules, either bound to the vesicular membrane or present in the solute matrix core. In adrenomedullary cells NE stored in vesicular storage granules can leak into the cytosol where enzyme phenylethanolamine N-methyrltransferrase (PNMT) is exclusively present and converts NE to epinephrine (E). (16,50) The formed E is translocated back into chromaffin granules. (17)

Another major enzyme vital in the metabolism of cathecholamines is catechol-O-methytransferase (COMT) which is present both extra- and intramedullary for conversion of DA to methoxytyramine (MTY), NE to normetanephrine (NMN), and E to metanephrine (MN).51 Ninety percent of MN and 23% of NMN in the circulation come from this pathway. (51-52) Sympathetic nerves contain the enzyme monoamine oxidase (MAO) which deaminates NE to 3-4-dihydroxyphenylglycol (DHPG). DHPG is methylated by COMT to 3-methoxy-4-hydroxyphenylglycol (MHPG), which is converted by aldehyde dehydrogenase (AD) in the liver to the metabolite vanillylmandelic acid (VMA), an end product of catecholamine metabolism in human urine. (53-54) The O-methylated metabolites of NE, E and DA are continuously released from PHEO and become major parameters to assess tumoral activity. (27,55-59)

Apart from being excreted in the urine, the free metanephrines are also conjugated in the wall of gastrointestinal tract by the enzyme sulfotransferase family, cytosolic, 1A phenol-preferring member 3 (SULT1A3). (60) These sulfate-conjugated forms of metanephrines prolong their plasma half-lives 30x higher than the free forms. (61-62) Measurements of urine metanephrines utilize an acid hydrolysis step to convert the sulfate-conjugated metabolites to free forms. Thus, such measurements reflect the total metanephrines (Fig. 2B). (6)

In pheochromocytoma, there are elevations of catecholamines and their metabolites specific for locations of lesions (adrenomedullary and extra-adrenal), abnormal tumor enzymatic activity (increased normetanephrine, metanephrine, and methoxytyramine) and altered pathway mechanisms. (6)

 

Early Diagnosis Of Pheochromocytoma

The two major factors for increased morbidity and mortality in PHEO are delay in the diagnosis63 and late detection of metastasis. (25) Recent developments addressed these concerns, such as improved biochemical analytical procedures, (6) analysis and recognition of evolving clinical presentations, (13,64-66) and inclusion of methoxytyramine in the work-up of PHEO, (17,67)  improved imaging modalities, (67-68)  and correlation of biochemical and imaging profiles with phenotype and genotype of the patients. (11)

 

Improved Sample Preparation, Specific Reference Values And Advanced Laboratory Methods

Catecholamines are measured in plasma and urine in several forms - as unconjugated norepinephrine, epinephrine, and dopamine, or by their O-methylated metabolites- normetanephrine, metanephrine, and methoxytyramine.6 Research institutions and commercial laboratories in most countries do not ordinarily measure these hormones and, therefore, have to be sent out through courier. It is imperative that preparation, collection, handling, storage and packaging of these specimens must be done with utmost care, caution, and precision so as not to alter the true values of the hormones. (69)

Prior to sample analysis, various important factors must be assessed in order to avoid or minimize false-positive and false-negative results, thus yielding better diagnostic accuracy. These factors are- age, position of the patient during blood extraction, immediate dietary intake, and current medications. (Table 1). (6,11,70-73) Values of plasma catecholamines and metanephrines have shown to approximate tumoral activity if blood extraction is done in the supine position.69-70,74 Dietary restrictions for tyramine-rich diet (cheese, nuts, cereal, beer, wine) are made mainly for the measurement of 3-methoxytyramine (MTY), a dopamine metabolite, and blood sample must be collected after an overnight fast. (71)

Co-morbidites have been reported also to influence plasma and urine MN and NMN results, such as renal failure, stroke or intracerebral hemorrhage, decompensated congestive heart failure and obstructive sleep apnea. (75) Stabilization of co-morbidities is imperative to avoid false low (renal failure) or inadvertently high values (decompesated heart failure, stroke, obstructive sleep apnea). (Table 2)  Plasma metanephrine has shown to be least affected by these conditions. (75)

Diagnostic specificity and sensitivity of biochemical tests rely significantly on cut-offs of measured values of plasma catecholamines and their metabolites. (76) Recently, Eisenhofer and his group established age-adjusted cut-offs of reference intervals for plasma normetanephrine and optimized cut-offs for metanephrine, minimizing false positive results, increasing diagnostic specificity to 96.0%, with minimal loss in diagnostic sensitivity of 93.6%. (16,77) Plasma metanephrine, but not normetanephrine, was higher in men but reference interval did not differ.  Upper cut-offs of reference intervals for normetanephrine increased from 0.47 nmol/L in children to 1.05 nmol in subjects older than 60 years (Table 3, Table 4). (16,77)

Equally important is the significant progress in the development of catecholamine assay methodology.6 Although immunoassays remain useful for measuring metanephrines (78-79) underestimation of plasma concentrations of metanephrines and normetanephrines have been reported.80 Recently, liquid chromatography with electrochemical detection (LC-ECD) or coupled to tandem mass spectrometry (LC-MS/MS) are currently becoming the preferred methods with favoring more of the latter. (81-84) Aside from having superior accuracy and precision of catecholamine measurement with LC-ECD and LS-MS/MS, (80,82-83) they allow fractionated measurements of normetanephrine and metanephrine vs. colorimetric and fluorometric of total metanephrines (combined normetaphrine and metanephrine). Furthermore, there is additional and important advantage of capability to measure 3-methoxytyramine (MTY), (80) a biomarker which importance will be highlighted in subsequent discussion.

Metabolomics, a global metabolite profiling, is a new technology of functional genomics used for investigating metabolite changes associated with some gene mutations. LC-MS/MS, gas chromatography- mass spectrometry (GC-MS), (85) ultrahigh pressure liquid chromatography with tandem mass spectrometry (UPHPLC-MS/MS), (30) 1H nuclear magnetic resonance (NMR) spectroscopy (86) and recently, a new technique, so-called 1H high-resolution magic angle spinning (HRMAS) nuclear magnetic resonance (NMR) spectroscopy87 have been employed with the advantages suited for small sample of tissues with no chemical extraction and manipulation. The modality showed promising usefulness in the clinical assessment specifically for SDHx-related tumors as a screening method and functional test for evaluating SDHx mutation of unknown pathogenicity. (87)

 

Evolving Clinical Presentation Of Pheochromocytoma

High index of suspicion remains the pivot point to initiate biochemical and imaging studies in patients suspected to have PHEO. The clinical presentation is defined by the biochemical secretory characteristic of the lesion, NE, EPI and their metabolites, (15-19) dictated by enzymatic profile of the tumor. (13) Basic knowledge on organ-specific role of adrenoceptors is necessary in order to understand responses to catecholamines which are magnified in patients with PHEO due to excess secretion of the hormones and their metabolites (Table 5).

Based on ligand studies and their agonists and antagonists, adrenoceptors are classified into adrenergic (α1, α2, β1, β2, β3) and dopamnergic recceptors (D1, D2) and their subtypes. Almost all tissues and organs of the body express these receptors.88 However, to date, there is no close relationship established between specific subtypes and signaling mechanisms. Each vascular structure may harbor mixtures of α1-adrenoceptor subtypes and may respond to the same stimuli at the same time. (89-91) On the other hand, the maximal b-mediated vasodilatation varies from vascular bed to vascular bed and depends on the tone of the tissue. (92-93)

Norepinephrine mainly signals α1, α2, and β1 receptors, while epinephrine mainly signals β1 and β2 receptors. Normally dopamine does not affect the adrenergic receptors, but with increased plasma concentrations, it can stimulate both α and β receptors. (13)

In general, alpha-1 receptors, mostly found in smooth muscle, peripheral arteries and veins cause vasoconstriction upon stimulation and increasing systemic pressure. In pheochromocytoma, manifestations include hypertension, headache, and pallor. Stimulation of α2-adrenergic receptors located on smooth muscles will result in arterial vasodilation and coronary vasoconstriction; in PHEO typical manifestations may include diaphoresis and orthostatic hypotension. Stimulation of β1-adrenergic receptors has a positive chronotrophic and inotropic effect in the heart and will also result in release of renin. In PHEO this can contribute to hypertension, palpitations, and tachycardia. Stimulation of β2-adrenergic receptors will induce vasodilation of muscular arteries, and some common effects in PHEO include constipation and nausea. β3-adrenergic receptors in adipocytes induces lipolysis and can cause weight loss in PHEO. (13,17,94)

Pourian and his group66 recently attempted to formulate the likelihood ratio (LR) of signs and symptoms to aid in PHEO diagnosis in the clinical setting. The most prevalent signs and symptoms were hypertension, headache, palpitation and diaphoresis. But based on their calculated LR, the significant symptoms that could aid in diagnosis were diaphoresis, palpitations, and headache alone, with the exclusion of hypertension.

The Sweden National Cancer Registry reported a 4x higher risk for mortality in PHEO compared to the general population with deaths occurring from acute hypertensive crisis. (63) Interestingly, Stolk et al., (65) have demonstrated that among PHEO vs. patients with essential hypertension, there is clearly a higher rate of cardiovascular (CV) events in PHEO excluding differences in hypertension and other CV risk factors. Recently, the literature have been showing case reports of young individuals in their 20's, unsuspected to harbor PHEO, presenting with dramatic CV events, with one succumbing to CV failure.95 Interestingly, CV anatomic and functional abnormalities reverse after adrenalectomy (Table 6). (95-96) This is similar to our case of 20-year old female diagnosed and operated for large malignant PHEO. Except for her hypertension of one year, she has no other risk factors for CVD. Her echocardiographic finding showed dyskinesia of the septum (Figure 3).

Early diagnosis of PHEO does not only resolve the catecholamine-induced cardiomyopathy with timely treatment but also the arterial stiffness. It has been shown that those PHEO patients whose diagnosis and treatment happened within 4 years from onset of hypertension do not require anti-hypertensive medications postoperatively as opposed to those whose onset of hypertension is 10 years or later from diagnosis and treatment. (97)  Interestingly, early diagnosis treated with mere unloading of the circulation with excess catecholamine by removing the dominant catecholamine-secreting lesion in patients with bilateral PHEO results into complete resolution of symptomatology, significant lowering to normalization of blood pressure, decrease in the number of antihypertensive medications, and better quality of life. (98-99)

It seems that the destructive effect of chronic hypercatecholaminemia happens insiduously if diagnosis of PHEO is overlooked, and dramatic CVD events and death occurs when there is sudden surge in the concentration of the hormones adding significant insult to a compromised cardiac function. This explosive cardiovascular picture of patients with PHEO may provide new insights in the paradigm shift in the clinical assessment of these patients. Research is warranted to demonstrate the value and cost-effectiveness of 2D echocardiogram, a test readily available, in the assessment and monitoring of patients with minimal or absent CVD risk factors and being suspected for PHEO but with vague clinical presentation and equivocal biochemical results. Cardiac MRI is worth doing in patients with severe clinical symptomatology of cardiac disease like dyspnea, orthopnea and chest pain and with evidence of myocardial damage in the ECG and elevated cardiac enzymes . (100)

 

Methoxytyramine: A Noble Biomarker For Early Diagnosis Of PHEO And Early Detection Of Metastasis

Until recently, the biggest challenge in the biochemical evaluation of PHEOs is those with minimal catecholamine secretion (101) or exclusively secreting dopamine (76) which often leads to delayed and missed diagnosis. These tumoral dopaminergic phenotype are also observed to be mostly extra-adrenal, metastatic, and associated with hereditary lesions.(17,26,77,102) The introduction of the measurement of plasma O-methylated dopamine metabolite, 3-methoxytyramine (MTY) made the evaluation of dopamine-producing PHEOs including their metastases possible and very useful, especially in those presenting with succinate dehydrogenase gene mutations. (17,26,77)

The measurement of 3-MTY discriminated two distinct groupings; 1) MEN2 and NF1 and 2) VHL and SDHx.77  Patients with VHL and SDH mutations harbor immature tumors and lack PNMT necessary for epinephrine secretion; therefore, they do not synthesize metanephrine (MN) but only normetanephrine (NMN) and/or 3- MTY. The best biomarker for SDH tumors is 3-MTY since this is produced only by these tumors. Since MEN2 and NF1 tumors secrete both NE and E, measurement of NMN and MN best distinguishes these two from VHL and SDH tumors.17,26 With combined measurements of NMN, MN and 3-MTY, patients with NF1 and MEN2 can be discriminated from those with VHL, SDHB and SDHD, and 3-MTY can discriminate SDHB and SDHD from VHL in 78% of cases.17,26 Gupta and his colleagues recently demonstrated that 50% of malignant PHEO have increased levels of both NM and 3-MTYgupta. (35)

PHEOs of the dopaminergic phenotype have generally been found to have reduced levels of the enzyme dopamine β-hydroxylase, which results in dopamine accumulation and a decreased production of norepinpephrine. (103-104) This finding may be due to proliferation of dedifferentiated progenitor cells giving rise to these tumors, as seen in patients with metastatic disease and with mutations in SDHB and SDHD.105 Patients with these mutations show increases in the levels of dopamine and methoxytyramine in addition to elevations in the level of normetanephrine. (77,106-107)

Biochemical secretory attributes of tumors using 3-MTY biomarker has been shown also to assist in deciphering location and metastasis. (26,77) In addition to being elevated in over two-thirds of patients with SDHB and SDHD mutations, 3-methoxytyramine is also a marker of multifocality and extra-adrenal in location. Together with a diagnosis of SDHB mutation, a 5-fold higher levels of 3-MTY signifies malignant nature of the tumor with metastasis. (26,77,108) Furthermore, although rare, cases of PHEOs in patients with NF1, VHL, MEN2A and MEN2B secreting high levels of dopamine and/or 3-methoxytyramine, have also been reported. (109-112)

 

Advanced Imaging Modalities

After catecholamine excess has been established biochemically, imaging studies for localization of primary tumor and determination of metastates should be done. The diagnosis pf pheochromocytoma is usually challenging due to the variety of clinical presentation and anatomic and functional imaging results. It is important to use the most appropriate available imaging modality, with good sensitivity without compromising specificity.

Anatomic imaging with the use of computerized tomography (CT) has been the preferred initial procedure for localization of PHEOs owing to its high sensitivity of 90%. (11,113) However, its limitation has been observed in extra-adrenal, recurrent and metastatic lesions. (114-115) MRI, on the other hand is more advantageous in detecting extra-adrenal lesions, and is indicated in those with allergy to contrast, pregnant or pediatric patients, and those whose contrast medium is a contraindication. (10) Ultrasound sensitivity is poor but very useful in the detection of liver metastasis and lesions in the urinary bladder. (116)

Table 7 reviews the sensitivity and specificity of imaging modalities in metastatic PHEO. Sensitivity of CT and MRI is variable. In a multicenter the study involving patients with adrenal malignancy, the sensitivity of contrast-enhanced CT (CECT) was found to be at 59% only. (117) In a study involving patients with biochemical catecholamine excess, the patient based sensitivity of CT/MRI was 67% with lesion-based sensitivity of 44%.118 In contrast, a study involving 216 patients suspected of pheochromocytoma and paraganglioma, it has been found that CT/MRI is highly sensitive, as high as 95.7% for nonmetastatic tumors and 74.4% in metastatic tumors. (119-120)

In contrast to anatomic imaging, functional imaging offers the advantage of higher specificity in detecting multifocal and metastatic tumors and can characterize tumoral metabolic activity.  (119-122) 123I- or 131I-metaiodobenzylguanidine (MIBG) scintigraphy has the structure similar to NE so it can enter cells thru NE transporters. 123I-MIBG is more sensitive and has better detection rate.68,116,123-124 On the other hand, single-photon emission computed chromatography (SPECT) has been used with CT/MRI for colocalization. A recent report has shown the highest sensitivity with 123I-MIBG SPECT/MRI in the detection of adrenal PHEOs, especially in cases where PHEO is ruled out. (125) With the advancement of imaging techniques, the limitation with MIBG becomes more apparent notably in missed metastasis yielding false-negative results in patients with succinate dehydrogenase subunit B (SDHB) mutations. (68,126) 124IMIBG is reserved for volume determination prior to 131IMIBG therapy for metastatic PHEO. (127)

Positron emission tomography (PET) is becoming widely used and offers favorable attributes, such as less imaging time, low radiation exposure, and superior spatial resolution. 18F-fluorodeoxyglucose (FDG) PET is the preferred procedure for malignant tumors, especially SDHB-related PHEO since cancer cells readily uptake glucose. (120) However, its performance is not specific since it can detect other kinds of tumors. (68)

18F-fluorodopamine (FDOPA) is a more specific tracer since structure is similar to dopamine, a catecholamine precursor, and therefore enters the cell through NE transporter. (116,124,128) This imaging modality has high sensitivity for metastatic tumors. (129-131) Newer PET scanning tracers have been developed and showed promising results in detection of metastasis and characterization of metabolic activity of the tumor cells namely the DOTA peptides- DOTATATE, DOTATOC, and DOTANOC. 68Ga-DOTATOC PET/CT was found superior to FDOPA PET/CT in the diagnosis of metastatic tumors.(132) Ongoing research is being undertaken to observe further these findings in a bigger cohort. For chromaffin tumors that express somatostatin receptors, 111In-DTPA octreotide or 111In DTPA-pentetreotide have proven useful. (68,133)

 

Conclusion and Insight

In this review, the diagnosis of pheochromocytoma is revisited to address the evolving clinical presentation that increases morbidity and mortality due to delay in diagnosis and treatment.  The discussion centered on the progress in the approaches of early diagnosis of PHEO through complete history and physical examination, and improved analytical approaches and inclusion of an important metabolite, methoxytyramine, in the biochemical assessment. We have also emphasized the introduction of cardiovascular imaging 2D echocardiogram and cardiac MRI in the early assessment of patients with equivocal biochemical and imaging results. In this aspect, as have been shown in previous reports, the resultant cardiomyopathy from chronic catecholaminemia is reversible and catecholamine unloading in the circulation leads to significant clinical improvement. We have also pointed out the advances in the imaging procedures, which led to better diagnostic accuracy in the early detection of metastasis and recurrence. Finally, we have elucidated how the clinical presentation, biochemical profile and imaging characteristics of PHEO correlated well with specific gene mutations. With the aforementioned progress we have come up with recommendations summarized in an algorithm shown in (Figure 4).

 

Declaration of Interests

The authors declare that there is no conflict of interest that could be perceived prejudicing the impartiality of this review.

 

Funding

The review did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.

 

Acknowledgement

We would like to thank the technical support of Ms. Jacquelin Ombac.

 

  1. Sutton MG, Sheps SG & Lie Ll. Prevalence of clinically unsuspected pheochromocytoma. Mayo Clinic Proceedings. 1981; 56 354-60.
  2. Sinclair AM, Isles CG, Brown I, Cameron H, Murray GD, & Robertson JW. Secondary hypertension in a blood pressure clinic. Archives of Internal Medicine. 1987; 147 1289-1293.
  3. Anderson GH, Jr., Blakeman N, Streeten DH. The effect of age on prevalence of secondary forms of hypertension in 4429 consecutively referred patients. Journal of Hypertension. 1994; 12 609-615.
  4. Eisenhofer G, JW Lenders, WM Linehan, MW Walther, DS Goldstein, & HR Keiser. Plasma normetanephrine and metanephrine for detecting pheochromocytoma in von hippel-lindau disease and multiple endocrine neoplasia type 2. New England Journal of Medicine. 1999; 340 1872-1879.
  5. Dluhy RG. Pheochromocytoma — death of an axiom. New England Journal of Medicine. 2002; 346 1486 -1488. doi: 10.1056/NEJM200205093461911.
  6. Eisenhofer G & Peitzsch M. Laboratory evaluation of pheochromocytoma and paraganglioma. Clinical Chemistry. 2014; 60 1486-1499; DOI: 10.1373/clinchem.2014.224832.
  7. Lance JW & Hinterberger H. The headached of pheochromocytoma. Proceedings of the Australian Association of Neurologists. 1975; 12 49-53.
  8. Manger WM & Gifford RW Clinical and experimental Pheochromocytoma. Second Edition.Blackwell Science; Cambridge1996.
  9. Young WF Jr & Maddox DE Spells:in search of cause. Mayo Clinic Proceedings 199570 757-765.
  10. Lenders JWM, Eisenhofer G, Mannelli M, & Pacak K. Phaeochromocytoma. Lancet .2005; 366 665–675.
  11. Lenders JWM & Eisenhofer G. Pathophysiology and diagnosis of disorders of the adrenal medulla: focus on pheochromocytoma. Comprehensive Physiology. 2014; 4 691-713. (10.1002/cphy.c130034).
  12. Gimenez-Roqueplo AP, Dahia PL & Robledo M. An update on the genetics of paraganglioma, pheochromocytoma, and associated hereditary syndromes. Hormone and Metabolic Research. 2012; 44 328-333.
  13. Zuber S, Kantorovich V, Pacak K. Hypertension in Pheochromocytoma: Characteristics and Treatment. Endocrinology Metabolism Clinics of North America. 2011; 40 295–311. (doi:10.1016/j.ecl.2011.02.002).
  14. Eng C, Clayton D, Schuffenecker I, Lenoir G, Cote G, Gagel RF, Ploos van Amstel HK, Lips CJM, Nishisho I, Takai SI et al. The Relationship Between Specific RET Proto-oncogene Mutations and Disease Phenotype in Multiple Endocrine Neoplasia Type 2International RET Mutation Consortium Analysis. Journal of American Medical Association. 1996; 276 1575-1579. doi:10.1001/jama.1996.03540190047028.
  15. Hernandez FC, Sanchez M, Alvarez A, Diaz J, Pascual R, Perez M, Tovar I & Martinez P. A five-year report on experience in the detection of pheochromocytoma. Clinical Biochemistry. 2000; 33 649–55.
  16. Eisenhofer G, Ehrhart-Bornstein M & Bornstein S. The adrenal medulla. physiology and pathophysiology. In: Bolis CL LJ, Govoni S, editor. Handbook of the Autonomic Nervous System in Health and Disease. 2003; pp. 185-224. New York, Basel: Marcel Dekker Inc.
  17. Eisenhofer G, Lenders JW, Timmers HJLM, Mannelli M, Grebe SK, Hofbauer LC, Bornstein SR, Tiebel O, Adams K, Bratslavsky G. Measurements of plasma methoxytyramine, normetanephrine, and metanephrine as discriminators of different hereditary forms of pheochromocytoma. Clinical Chemistry. 2011; 57 411-420.
  18. Kudva YC, Sawka AM & Young WF Jr. The Laboratory Diagnosis of Adrenal Pheochromocytoma: The Mayo Clinic. Journal of Clinical Endocrinology & Metabolism. 2003; 88.
  19. Boyle JG, Davidson DF, Perry CG & Connell JM. Comparison of diagnostic accuracy of urinary free metanephrines, vanillyl mandelic acid, and catecholamines and plasma catecholamines for diagnosis of pheochromocytoma. Journal of Clinical Endocrinology & Metabolism. 2007; 92 4602–4608.
  20. Erlic Z, Rybicki L, Peczkowska M, Golcher H, Kann PH, Brauckhoff M, Mussig K, Muresan M, Schaffler A, Reisch N et al. European-American Pheochromocytoma Study G. Clinical predictors and algorithm for the genetic diagnosis of pheochromocytoma patients. Clinical Cancer Research. 2009; 15 6378-6385.
  21. Zhuang Z, Yang C, Lorenzo F, Merino M, Fojo T, Kebebew E, PopovicV, Stratakis CA, Prchal JT & Pacak K. Somatic HIF2A gain-of-function mutations in paraganglioma with polycythemia. New England Journal of Medicine. 2012; 367 922-930.
  22. Dahia PLM. The genetic landscape of pheochromocytomas and paraganglioms: somatic mutations take center stage. Journal of Endocrinology & Metabolism. 2013; 98 2679-2681.
  23. Lorenzo FR, Yang C, Ng Tang Fui M, Vankayalapati H, Zhuang Z, Huynh T, Grossmann M, Pacak K & Prchal JT. A novel EPAS1/HIF2A germline mutation in a congenital polycythemia with paraganglioma. Journal of Molecular Medicine (Berl). 2013;91 507-512.
  24. Pacak K, Linehan WM, Eisenhofer G, Walther MW & Goldstein DS. Recent advances in genetics, diagnosis, localization and treatment of pheochromocytoma. Annals of Internal Medicine. 2001; 134 315-329.
  25. Timmers HJLM, Pacak K, Huynh TT, Abu-Asab M, Tsokos M, Merino MJ, Baysal BE, Adams KT & Eisenhofer G. Biochemically silent abdominal paragangliomas in patients with mutations in the succinate dehydrogenase subunit B gene. Journal of Clinical Endocrinology & Metabolism. 2008; 93 4826-4832.
  26. Eisenhofer G, Lenders JW, Timmers HJLM, Mannelli M, Grebe SK, Hofbauer LC, Bornstein SR, Tiebel O, Adams K, Bratslavsky G. Measurements of plasma methoxytyramine, normetanephrine, and metanephrine as discriminators of different hereditary forms of pheochromocytoma. Clinical Chemistry. 2011; 57 411-420.
  27. Eisenhofer G, Lenders JW, Siegert G, Bornstein SR, Friberg P, Milosevic D, Mannelli M, Linehan WM, Adams K, Timmers HJLM et al. Plasma methoxytyramine: a novel biomarker of metastatic pheochromocytoma and paraganglioma in relation to established risk factors of tumour size, location and SDHB mutation status. European Journal of Cancer. 2012; 48 1739-1749. (doi:10.016/j.ejca .2011.07.016).
  28. Eisenhofer G Pathophysiology and diagnosis of disorders of the adrenal medulla: focus on pheochromocytoma. Comprehensive Physiology. 2014; 4 691-713. (10.1002/cphy.c130034)
  29. Eisenhofer G & Peitzsch M. Laboratory evaluation of pheochromocytoma and paraganglioma. Clinical Chemistry. 2014; 60 1486-1499; DOI: 10.1373/clinchem.2014.224832.
  30. Richter S, Peitzsch M, Rapizzi E, Lenders JW, Qin N, de Cubas AA, Schiavi F, Rao JU, Beuschlein F, Quinkler M et al. Krebs cycle metabolite profiling for identification nd stratification of pheochromocytomas/paragangliomas due to succinate dehydrogenase deficiency. Journal of Endocrinology & Metabolism. 2014; 99 3903-3911.
  31. Janssen I, Blanchet EM, Adams K, Chen CC, Millo CM, Herscovitch P, Taieb D, Kebebew E, Lehnert H, Fojo AT et al Superiority of [68Ga]-DOTATATE PET/CT to Other Functional Imaging Modalities in the Localization of SDHB-Associated Metastatic Pheochromocytoma and Paraganglioma. Clinical Cancer Research. 2015; 21 3888-3895.
  32. Yang C, Zhuang Z, Fliedner SMJ, Shankavaram U, Sun MG, Bullova P, Zhu R, Elkahloun AG, Kourlas PJ, Merino M et al. Germ-line PHD1 and PHD2 mutations detected in patients with pheochromocytoma/paraganglioma-polycythemia. Journal of Molecular Medicine. 2015; 93 93-104.
  33. Toledo RA, Qin Y, Cheng Z, Gao Q, Iwata S, Silva GM, Prasad M, Ocal T, Rao S, Aronin N et al Recurrent mutations of chromatin-remodeling genes and kinase receptors in pheochromocytoma and paragangliomas. Clinical Cancer Research. 2016; OF1 – OF11.
  34. Rowbotham DA, Enfield KSS, Martinez VD, Thu KL, Vucic EA, Stewart GL, Bennewith KL & Lam WL . Multiple components of the VHL tumor suppressor complex are frequently affected by DNA copy number loss in pheochromocytoma. International Journal of Endocrinology .2014; 1-9.
  35. Gupta P, Khurana ML, Khadgaawat R, Kumar G & Tandon. Plasma metanephrine, normetanephrine, and 3-methoxytyramine for the diagnosis of pheochromocytoma. Indian Journal of Endocrinology and Metabolism. 2015; 19 663-638.
  36. LeDouarin & Kalcheim 2nd ed The Neural Crest Cambridge University Press, Cambridge1999.
  37. Shtukmaster S, Schier MC, Huber K, Krispin S, Kalchiem C & Unsicker Klaus Sympathetic neurons and chromaffin cells share a common progenitor in the neural crest in vivo. Neural Development .2003; 8 12.
  38. Huber K, Kalcheim C & Unsicker K. The development of the chromaffin cell lineage from the neural crest. Autonomic Neuroscience. 2009; 151 10-16.
  39. Rohrer H . Transcriptional control of differentiation and neurogenesis in autonomic ganglia. European Journal of Neuroscience. 2011; 34 1563-1573.
  40. Unsicker K, Huber K, Schober A & Kalcheim C. Resolved and open issues in chomaffin cell development. Mechanism of Development. 2013; 130 324-329.
  41. Konno H, Handa T & Alonzo D, Taylor. Effect of polymer type on the dissolution profile of amorphous solid dispersions containing felodipine. European Journal of Pharmaceutics and Biopharmaceutics. 2008;70 493-499.
  42. Unsicker K, Krisch B, Otten U & Thoenen H. Nerve growth factor-induced fiber outgrowth from isolated rat adrenal medullary cells: impairment by glucocorticoids. Proceedings of the National Academy of Sciences of the United States of America. 1978; 74 3498-3504.
  43. Anderson DJ. Molecular control of cell fate in the sympathoadrenal cell lineage. Annual Review of Neurology Science. 1993; 16 129-158.
  44. Michelson AM & Anderson DM. Changes in competence determine the timing of the two sequential glucocorticoid effects on sympathoadrenal progenitors. Neuron. 1993; 8 589-604.
  45. Unsicker K. The chromaffin cell: paradigm in cell, developmental and growth factor biology. Journal of Anatomy. 1993; 183 207-221.
  46. Unsicker K, Stahnke G, & Muller TH. Survival,morphology,and cathecolamine storage of chromaffin cells serum-free culture: evidence for a survival and differentiation promoting activity in medium conditioned by purified chromaffin cells. Neurochemistry Residence .1987; 12 995-1003.
  47. Finotto S, Krieglstein K, Schober A, Deimling F, Lindner K, Bruhl B, Beier K, Metz J, Garcia-Arraras JE, Roig-Lopez J et al. Analysis of mice carrying targeted mutations of the glucocorticoid receptor gene argues against an essential role of glucocorticoid signalling for generating adrenal chromaffin cells. Development. 1999; 126: 2935-2944.
  48. Nagatsu T, Levitt M & Udenfriend S. Tyrosine hydroxylase: The Initial step in norepinephrine biosynthesis. Journal of Biological Chemistry. 1964; 239:2910-2917.
  49. Eisenhofer G, Goldstein DS, Walther MM, Friberg P, Lenders JW, Keiser HR & Pacak K. Biochemical diagnosis of pheochromocytoma: how to distinguish true- from false-positive test results. Journal of Clinical Endocrinology & Metabolism. 2003b; 88 2656–2666. (doi:10.1210/ jc.2002-030005).
  50. Livett BG. Adrenal medullary chromaffin cells in vitro. Physiological Reviews. 1984; 64 1103-1161.
  51. Eisenhofer G, Rundquist B, Aneman A, Friberg P, Dakak N, Kopin IJ, Jacobs MC, & Lenders JW Regional release and removal of catecholamines and extraneuronal metabolism to metanephrines. Journal of Clinical Endocrinology & Metabolism. 1995b; 80: 3009-3017.
  52. Eisenhofer G, Friberg P, Pacak K, Goldstein DS, Murphy DL, Tsigos C, Quyyumi AA, Brunner HG & Lenders JW. Plasma metadrenalines: Do they provide useful information about sympatho-adrenal function and catecholamine metabolism? Clinical Science (Lond). 1995a; 88: 533-542.
  53. Eisenhofer G, Pecorella W, Pacak K, Hooper D, Kopin I & Goldstein D. The neuronal and extraneuronal origins of plasma 3-methoxy-4-hydroxyphenylgycol in rats. The Journal of Auto-Nomic Nervous System. 1994; 50 93-107.
  54. Eisenhofer G, Huynh TT, Hiroi M & Pacak K. Understanding catecholamine metabolism as a guide to the biochemical diagnosis of pheochromocytoma. Reviews in Endocrine and Metabolic Disorders. 2001a; 2: 297-311.
  55. Sjoerdsma A, King WM, Leeper L & Udenfriend S. Demonstration ofthe 3-methoxy analog of norepinephrine in man. Science. 1957;127 876.
  56. Sjoerdsma A. Catecholamine metabolism in patients with pheochromocytoma. Pharmacological Reviews. 1959;11 :374-378.
  57. Crout JR & Sjoerdsma A. Turnover and metabolism of catecholamines in patients with pheochromocytoma. Journal of Clinical Investigation. 1964; 43: 94-102.
  58. Eisenhofer G, Keiser H, Friberg P, Mezey E, Huynh TT, Hiremagalur B, Ellingson T, Duddempudi S, Eijsbouts A, Lenders JW. Plasma metanephrines are markers of pheochromocytoma produced by catechol-O-methyltransferase within tumors. Journal of Clinical Endocrinology & Metabolism. 1998; 83: 2175-2185.
  59. Eisenhofer G, Goldstein DS, Sullivan P, Csako G, Brouwers FM, Lai EW, Adams KT & Pacak K . Biochemical and clinical manifestations of dopamine-producing paragangliomas: utility of plasma methoxytyramine. Journal of Clinical Endocrinology & Metabolism. 2005; 90 2068-2075.
  60. Goldstein DS, Swoboda KJ, Miles JM, Coppack SW, Aneman A, Holmes C, Lamensdorf I & Eisenhofer G. Sources and physiological significance of plasma dopamine sulfate. Journal of Clinical Endocrinology & Metabolism. 1999; 87: 2523-2531.
  61. Lenders JW, Keiser HR, Goldstein DS, Willemsen JJ, Friberg P, Jacobs MC, et al. Plasma metanephrines in the diagnosis of pheochromocytoma. Annals of Internal Medicine. 1995;123:101-109.
  62. Pamporaki C, Darr R, Bursztyn M, Glockner S, Bornstein SR, Lenders JWM, et al. Plasma-free vs deconjugated metanephrines for diagnosis of phaeochromocytoma. Clinical Endocrinology (Oxford). 2013;79:476-483.
  63. Khorram-Manesh A, Ahlman H, Nilsson O, Odén A & Jansson S. Mortality associated with pheochromocytoma in a large Swedish cohort. European Journal of Surgical Oncology. 2004; 30: 556-559.
  64. Pacak K. Pheochromocytoma: a catecholamine and oxidative stress disorder. Endocrine Regulations. 2011; 45: 65–90.
  65. Stolk RF, Bakx C, Mulder J, Timmers HJLM & Lenders JWM. Is the excess cardiovascular morbidity in pheochromocytoma related to blood pressure or to catecholamines? Journal of Clinical Endocrinology & Metabolism. 2013; 98 1100-6 doi: 10.1210/jc.2012-3669.
  66. Pourian M, Mostafazadeh DB & Soltani A. Does ths patient have pheochromocytoma? A systematic review of clinical signs and symptoms. Journal of Diabetes & Metabolic Disorders .2016; 15:1-12.
  67. Maurice JB, Troke R, Win Z, Ramachandran R, Al-Nahhas A, Naji M, et al. A comparison of the performance of 68Ga-DOTATATE PET/CT and 123I-MIBG SPECT in the diagnosis and follow-up of phaeochromocytoma and paraganglioma. European Journal Nuclear Medicine and Molecular Imaging. 2012; 39:1266-1270.
  68. Taieb D, Neumann HP, Rubello D, Al-Nahhas A, Guillet B & Hindie E. Modern nuclear imaging for paragangliomas: Beyond SPECT. Journal of Nuclear Medicine. 2012; 53:264-274.
  69. Lenders JWM, Willemsen JJ, Eisenhofer G, Ross HA, Pacak K, Timmers HJLM & Sweep CG. Is supine rest necessary before blood sampling for plasma metanephrines? Clinical Chemistry.2007; 53: 352-354.
  70. Tulen JH, Boomsma F & Man In’t Veld AJ. Cardiovascular control and plasma catecholamines during rest and mental stress: effects of posture. Clinical Science (London).1999; 96: 567-576.
  71. de Jong W, Eisenhofer G, Post W, Muskiet F, de Vries E, & Kema I. Dietary influences on plasma and urinary metanephrines: implications for diagnosis of catecholamine-producing tumors. Journal of Clinical Endocrinology & Metabolism. 2009; 94: 2841–2849.
  72. van Berkel A, Lenders J & Timmers HJLM. Biochemical diagnosis of phaeochromocytoma and paraganglioma. European Journal of Endocrinology. 2014; 170: R109–R119.
  73. Eisenhofer G, Peitzsch M & McWhinney B. Impact of LC-MS/MS on the laboratory diagnosis of catecholamine producing tumors. Trends in Analytical Chemistry. 2016; 1-11 (doi: 10.1016/j.trac.2016.01.027)
  74. Esler M, Jennings G, Korner P, Willett I, Dudley F, Hasking G, Anderson W & Lambert G. Assessment of human sympathetic nervous system activity from measurements of norepinephrine turnover. Hypertension. 1988; 11: 3-20.
  75. Dobri G, Bravo E & Hamrahian A. Pheochromocytoma: pitfalls in the biochemical evaluation. Expert Review of Endocrinology &. Metabolism. 2014; 9:123–135.
  76. Sawka AM, Jaeschke R, Singh RJ & Young WF Jr. A comparison of biochemical tests for pheochromocytoma: measurement of fractionated plasma metanephrines compared with the combination of 24-hour urinary metanephrines and catecholamines. Journal of Clinical Endocrinology & Metabolism. 2003; 88: 553-558.
  77. Eisenhofer G, Lenders JW, Siegert G, Bornstein SR, Friberg P, Milosevic D, et al. Plasma methoxytyramine: a novel biomarker of metastatic pheochromocytoma and paraganglioma in relation to established risk factors of tumour size, location and SDHB mutation status. European Journal of Cancer. 2012; 48: 1739-1749. (doi:10.016/j.ejca .2011.07.016).
  78. Unger N, Pitt C, Schmidt IL, Walz MK, Schmid KW, Philipp T, Philipp T, et al. Diagnostic value of various biochemical parameters for the diagnosis of pheochromocytoma in patients with adrenal mass. European Journal of Endocrinology. 2006; 154: 409–17.
  79. Pussard E, Chaouch A, Said T. Radioimmunoassay of free plasma metanephrines for the diagnosis of catecholamine-producing tumors. Clinical Chemistry and Laboratory Medicine. 2014; 52: 437–44.
  80. Pillai D, & Callen S. Pilot quality assurance programme for plasma metanephrines. Annals of Clinical Biochemistry. 2010; 47:137–42.
  81. Whiting MJ. Simultaneous measurement of urinary metanephrines and catecholamines by liquid chromatography with tandem mass spectrometric detection. Annals of Clinical Biochemistry. 2009; 46: 129–36.
  82. Peitzsch M, Pelzel D, Glockner S, Prejbisz A, Fassnacht M, Beuschlein F, et al. Simultaneous liquid chromatography tandem mass spectrometric determination of urinary free metanephrines and catecholamines, with comparisons of free and deconjugated metabolites. Clinica Chimica Acta. 2013 ; 418: 50–8a.
  83. Peitzsch M, Prejbisz A, Kroiss M, Beuschlein F, Arlt W, Januszewicz A, et al. Analysis of plasma 3-methoxytyramine, normetanephrine and metanephrine by ultraperformance liquid chromatography-tandem mass spectrometry: utility for diagnosis of dopamine-producing metastatic phaeochromocytoma. Annals of Clinical Biochemistry. 2013; 50: 147–55b.
  84. Lagerstedt SA, O’Kane DJ & Singh RJ. Measurement of plasma free metanephrine and normetanephrine by liquid chromatography-tandem mass spectrometry for diagnosis of pheochromocytoma. Clinical Chemistry.2004; 50: 603–11.
  85. Lendvai N, Pawlosky R, Bullova P, et al. Succinate-to-fumarate ratio as a new metabolic marker to detect the presence of SDHB/D-related paraganglioma: initial experimental and ex vivo findings. Endocrinology. 2014;155:27-32.
  86. Rao JU, Engelke UF, Sweep FC, et al. Genotype-specific differences in the tumor metabolite profile of pheochromocytoma and paraganglioma using untargeted and targeted metabolomics. J Clin Endocrinol Metab. 2015;100:E214-222.
  87. Imperiale A, Moussallieh FM, Roche P, et al. Metabolome profiling by HRMAS NMR spectroscopy of pheochromocytomas and paragangliomas detects SDH deficiency: clinical and pathophysiological implications. Neoplasia. 2015;17:55-65.
  88. Guimarães S & Moura D. Vascular adrenoceptors: an update. Pharmacological Reviews. 2001; 53 :319-356.
  89. Ruffolo RR, Jr. and Hieble JP. Adrenoceptor pharmacology: Urogenital applications. European Urology . 1999 ;36: 17-22.
  90. Zhong H & Minneman K. α1-Adrenoceptor subtypes. European Journal of Pharmacology . 1999; 37: 5261-276.
  91. Agryle SA& McGrath JC . An α1A/α1L-Adrenoceptor Mediates Contraction of Canine Subcutaneous Resistance Arteries. Journal of Pharmacology And Experimental Therapeutics . 2000 ; 295: 627-633.
  92. Guimaraes S, Brandao F, & Paiva MQ. A study of the adrenoceptor-mediated feedback mechanisms by using adrenaline as a false transmitter. Naunyn-Schmiedeberg's Archives of Pharmacology. 1978; 305: 185-188.
  93. Begonha R, Moura D & Gemaraes S. Vascular β-Adrenoceptor-mediated Relaxation and the Tone of the Tissue in Canine Arteries. Journal of Pharmacy and Pharmacology. 1995; 510-513. (doi: 10.1111/j.2042-7158.1995tb05840).
  94. Gardner D & Shoback D. Pheochromocytoma and paraganglioma. Basic Clinical Endocrinology edn 9. Greenspans. Lange 2011.
  95. de Miguel Vl, Arias A, Paissan A,Pérez de Arenaza D, Pietrani M, Jurado A, Jaén A & Fainstein Day P. Catecholamine-Induced Myocarditis in Pheochromocytoma. Circulation. 2014; 129: 1348-1349. (doi: 10.1161/CIRCULATIONAHA.113.002762).
  96. Sanchez-Recalde A, Costero O, Oliver JM, Iborra C, Ruiz E & Sobrino JA. Pheochromocytoma-related cardiomyopathy inverted Takotsubo contractile pattern. Circulation. 2006; 113 e738-e739.doi 10.1161/CIRCULATIONAHA.105.581108.
  97. Mercado-Asis LB, Tingcungco AG, Bolong DT, Lopez RA, Caguioa EV, Yamamoto ME, et al. Diagnosis of small adrenal pheochromocytoma by adrenal venous sampling with glucagon stimulation test. International Journal of Endocrinology and Metabolism. 2011; 9 :323-329.
  98. Malong CHP, Tanchee-Ngo MJ, Torres-Salvador P, Pacak K & Mercado-Asis LB. Removal of dominant adrenal lateralized by glucagon-stimulated adrenal venous sampling alleviates hypertension in bilateral pheochromocytoma. Journal of Life Sciences. 2013; 7: 586-591.
  99. Zhou G, et al. Diagnosis and surgical treatment of multiple endocrine neoplasia. Chinese Medical Journal.2009;122(13):1495-1500.
  100. Friedrich MG, Sechtem U, Schulz-Menger J, Holmvang G, Alakija P, Cooper LT, White JA, Abdel-Aty H, Gutberlet M, Prasad SJ et al. Cardiovascular magnetic resonance in myocarditis: a JACC white paper. Journal of the American College of Cardiology 2009.53: 1475-1487.
  101. Dubois LA & Gray DK Dopamine-secreting pheochromocytomas: in search of a syndrome. World Journal of Surgery. 2005;29: 909-913.
  102. Amar L, Peyrard S, Rossignol P, Zinzindohoue F, Gimenez-Roqueplo AP, et al. Changes in urinary total metanephrine excretion in recurrent and malignant pheochromocytomas and secreting paragangliomas. Annals of the New York Academy of Sciences. 2006; 1073: 383-391. (doi:10.1196/annals.1353.042).
  103. Feldman JM. Phenylethanolamine-N-methyltransferase activity determines the epinephrine concentration of pheochromocytomas. Research Communications in Chemical Pathology and Pharmacology Journal. 1981 ; 34: 389–398.
  104. Yasunari K, Kohno M, Yoshikawa J. A dopamine-secreting pheochromocytoma. American Journal of Medicine. 1999; 106: 599-600.
  105. Schlumberger M, Gicquel C, Lumbroso J, Tenenbaum F, Comoy E, Bosq J, et al. Malignant pheochromocytoma: clinical, biological, histologic and therapeutic data in a series of 20 patients with distant metastases. Journal of Endocrinogical Investigation 2002; 15: 631-642.
  106. Timmers HJ, Kozupa A, Eisenhofer G, et al. Clinical presentations, biochemical phenotypes, and genotype-phenotype correlations in patients with succinate dehydrogenase subunit B-associated pheochromocytomas and paragangliomas. Journal of Clinical Endocrinology & Metabolism. 2007; 92: 779-786.
  107. Kimura N, Miura Y, Nagatsu I & Nagura H. Catecholamine synthesizing enzymes in 70 cases of functioning and non-functioning phaeochromocytoma and extra-adrenal paraganglioma. Virchows Arch. A Pathology Anatomy and Histopathology. 1992; 421: 25–32.
  108. Turkova H, Prodanov T, Maly M, Martucci V, Adams K, Widimsky J Jr, et al. Characteristic and outcomes of metastatic SDHB and sporadic pheochromocytoma/paraganglioma: A National Institutes of Health study. Endocrine Practice. 2016; 22: 302-312.
  109. Palmar I, Vircburger M, Manojlovic D, Radevic B, Andjelkovic Z, Buric B, et al. [The von Hippel-Lindau syndrome with pheochromocytoma]. Srpski Arhiv Celokupno Lekarstvo . 2002 ; 2: 43-46.
  110. Figueroa SC, Khan U, Kurukulasuriya LR, Gardner D & Sowers JR. Surgical cure of hypertension in a patient with MEN 2A syndrome and mixed dopamine, metanephrine pheochromocytoma. Journal of Clinical Hypertension (Greenwich) 2010 ; 12: 439- 443.
  111. Dubey RK, Verma N & Pandey CK. Anaesthetic management of a dopamine-secreting phaeochromocytoma in multiple endocrine neoplasia 2B syndrome. Indian Journal of Anaesthesia. 2014; 58: 217-219.
  112. Teasdale S, & Reda E. Neurofibromatosis-related phaeochromocytoma: two cases with large tumours and elevated plasma methoxytyramine. Endocrinology Diabetes & Metabolism Case Reports .2015; 150-159.
  113. Ilias I, Sahdev A, Reznek RH, Grossman AB & Pacak K. The optimal imaging of adrenal tumours: a comparison of different methods. Endocrine- Related Cancer. 2007;14: 587-599. (doi: 10.1677/ERC-07-0045).
  114. Jalil ND, Pattou FN, Combemale F, Chapuis Y, Henry JF, Peix JL & Proye CA. Effectiveness and limits of preoperative imaging studies for the localisation of pheochromocytomas and paragangliomas: A review of 282 cases. French Association of Surgery (AFC), and The French Association of Endocrine Surgeons (AFCE). European Journal of Surgery.1998; 164: 23-28.
  115. Sahdev A, Sohaib A, Monson JP, Grossma AB, Chew SL, & Reznek RH. CT and MR imaging of unusual locations of extra-adrenal paragangliomas (pheochromocytomas). European Radiology.2005;15: 85-92.
  116. Leung K, Stamm M, Raja A & Low G. Pheochromocytoma: the range of appearances on ultrasound, CT, MRI, and functional imaging. AJR American Journal of Roentgenology . 2013; 200: 370–378. (doi: 10.2214/AJR.12.9126).
  117. Cistaro A, Niccoli Asabella A, Coppolino P, Quartuccio N, Altini C, Cucinotta M, et al. Diagnostic and prognostic value of ¹8F-FDG PET/CT in comparison with morphological imaging in primary adrenal gland malignancies - a multicenter experience. Hellenic Journal of Nuclear Medicine. 2015; 18: 97-102.
  118. Fiebrich HB, Brouwers AH, Kerstens MN, Pijl ME, Kema IP, de Jong JR, et al. 6-F-18Fluoro-L-dihydroxyphenylalanine positron emission tomography is superior to conventional imaging with ¹²³I-metaiodobenzylguanidine scintigraphy, computer tomography, and magnetic resonance imaging in localizing tumors causing catecholamine excess. Journal of Clinical Endocrinology & Metabolism. 2009; 94: 922-30. doi: 10.1210/jc.2009-1054. Epub 2009 Jul 21.
  119. Timmers HJLM, Chen CC, Carrasquillo JA, Whatley M, Ling A, Eisenhofer G, et al. Staging and functional characterization of pheochromocytoma and paraganglioma by ¹8F-fluorodeoxyglucose (¹8F-FDG) positron emission tomography. Journal of National Cancer Institute . 2012 ;104: 700-8. (doi: 10.1093/jnci/djs188). Epub 2012 Apr 18.
  120. Timmers HJLM, TaiebD & Pacak K. Current and future anatomical and functional imaging approaches to pheochromocytoma and paraganglioma. Hormone and Metabolic Research. 2012 ; 44: 367-372.
  121. King KS, Prodanov T, Kantorovich V, Fojo T, Hewitt JK, Zacharin M, et al. Metastatic pheochromocytoma/paraganglioma related to primary tumor development in childhood or adolescence: Significant link to SDHB mutations. Journal of Clinical Oncology. 2011; 29: 4137-4142.
  122. Martucci VL, Pacak K. Pheochromocytoma and paraganglioma: diagnosis, genetics, management, and treatment. Current Problems in Cancer. 2014; 38: 7-41. doi: 10.1016/j.currproblcancer.2014.01.001.
  123. Furuta N, Kiyota H, Yoshigoe F, Hasegawa N, & Ohishi Y. Diagnosis of pheochromocytoma using ¹²³I-compared with ¹³¹I-metaiodobenzylguanidine scintigraphy. International Journal of Urology . 1999 ; 6:119–124.
  124. Chen CC & Carrasquillo JA . Molecular imaging of adrenal neoplasms. Journal of Surgical Oncology. 2012; 106: 532–542.
  125. Derlin T, Busch JD, Wisotzki C, Schoennagel BP, Bannas P, Papp L, & Habermann CR. Intraindividual comparison of ¹²³I-mIBG SPECT/MRI,¹²³I-mIBG SPECT/CT, and MRI for the detection of adrenal pheochromocytoma in patients with elevated urine or plasma catecholamines. Clinical Nuclear Medicine 2013 ; 38: e1–6.
  126. Fonte J, Robles J, Chen C, Reynolds J, Whatley M, Ling A, Mercado-Asis LB, et al. False-negative ¹²³I-MIBG SPECT is most commonly found in SDHB-related pheochromocytoma or paraganglioma with high frequency to develop metastatic disease. Endocrine-Related Cancer. 2012; 13: 83-93.
  127. Hartung-Knemeyer V, Rosenbaum-Krumme S, Buchbender C, Pöppel T, Brandau W, Jentzen W, et al. Malignant pheochromocytoma imaging with 124IMBG PET/MR. Journal of Clinical Endocrinology & Metabolism . 2012; 97: 3833-4. (doi: 10.1210/jc.2012-1958. Epub 2012 Sep 7).
  128. Luster M, Karges W, Zeich K, Pauls S, Verburg FA, Dralle H, et al. Clinical value of 18F-fluorodihydroxyphenylalanine positron emission tomography/computed tomography (18F-DOPA PET/CT) for detecting pheochromocytoma. Thyroid . 2010; 20:527-33. doi: 10.1089/thy.2009.0342.
  129. Zelinka T, Timmers HJLM, Kozupall A, Chen CC, Carrasquillo JA, Reynolds JC, et al. Role of positron emission tomography and bone scintigraphy in the evaluation of bone involvement in metastatic pheochromocytoma and paraganglioma: specific implications for succinate dehydrogenase enzyme subunit B gene mutations. Endocrine-Related Cancer. 2008; 15:311-323.
  130. Timmers HJLM, Chen CC, Carrasquillo JA, Whatley M, Ling A, Havekes B, et al. Comparison of 18F-fluoro-L-DOPA, 18Ffluoro-deoxyglucose, and 18F-fluorodopamine PET and ¹²³I-MIBG scintigraphy in the localization of pheochromocytoma and paraganglioma. Journal of Clinical Endocrinology & Metabolism. 2009 ;94: 4757– 4767.
  131. Timmers HJLM, Eisenhofer G, Carrasquillo JA, Chen CC, Whatley M, Ling A, et al. Use of 18F]-fluorodopamine positronemission tomography (PET) as first-line investigation for the diagnosis and localization of nonmetastatic and metastatic phaeochromocytoma (PHEO). Clinical Endocrinology (Oxford). 2009; 71: 11–17.
  132. Peitzsch M, Prejbisz A, Kroiss M, Beuschlein F, Arlt W, Januszewicz A, et al. Analysis of plasma 3-methoxytyramine, normetanephrine and metanephrine by ultraperformance liquid chromatography-tandem mass spectrometry: utility for diagnosis of dopamine-producing metastatic phaeochromocytoma. Annals of Clinical Biochemistry .2013 ;50 :147–55b.
  133. Gimenez-Roqueplo AP, Caumont-Prim A, Houzard C, Hignette C, Hernigou A, Halimi P, et al. Imaging work-up for screening of paraganglioma and pheochromocytoma in SDHx mutation carriers: A multicenter prospective study from the PGL.EVA Investigators. Journal of Clinical Endocrinology & Metabolism. 2013 ; 98: E162-173.
  134. Eisenhofer G, Lattke P, Herberg M, Siegert G, Qin N, Da¨rr R, et al. Reference intervals for plasma free metanephrines with an age adjustment for normetanephrine for optimized laboratory testing of phaeochromocytoma. Ann Clin Biochem. 2013; 50: 62–69.

 

Table 1. Sample preparation, collection, and storage for hormonal tests in pheochromocytoma

Hormonal test/s

Preparation & Collection

Storage

Norepinephrine

& Epinephrine

                Plasma

 

 

 

                Urine

 

 

 

Dopamine

                Plasma

 

 

 

 

                Urine

 

 

 

 

Supine at least 20 mins

With an indwelling cannula

 

Tubes with heparin or EDTA

Placed on ice

Stored until -20 ⁰C, perform assay within 30 days

 

Containers with HCI

Light-proof containers

Storage at 4 ⁰C, long-term storage at -20 ⁰C or lower

 

Overnight fast

Avoid amine-rich foods* for

24 hrs

Supine at least 30 mins

With an indwelling cannula

 

Tubes with heparin or EDTA

Placed on ice

Stored until -20 ⁰C, perform assay within

30 days

 

Avoid amine-rich foods for

24 hrs

 

 

 

Containers with HCI

Light-proof containers

Storage at 4 ⁰C, long-term storage at

-20 ⁰C or lower

Normetanephrine

& Metanephrine

                Plasma

 

 

 

                Urine

 

 

 

 

Methoxytyramine

                Plasma

 

 

 

                Urine

Supine at least 30 mins

With an indwelling cannula

 

Tubes with heparin or EDTA

Placed on ice

Stored until -20 ⁰C, perform assay within

30 days

 

Acidification of sample not needed

Light-proof containers

Storage at 4 ⁰C, long-term storage at

-20 ⁰C or lower

 

 

Overnight fast

Avoid amine rich foods

Supine at least 30 mins

With an indwelling cannula

Avoid amine rich foods

 

Tubes with heparin or EDTA

Placed on ice

Stored until – 20 ⁰C, perform assay within

30 days

Acidification of sample not needed

Light-proof containers

Storage at 4 ⁰C, long-term storage at

-20 ⁰C or lower

*Amine-rich foods: beer, wine, cheese, bananas, pineapple, nuts, cereals

 

Table 2. Precautionary measures in the sample preparation and biochemical interpretation of results in pheochromocytoma

Clinical setting

Effect on Plasma and Urine NMN, MN or MTY

Precautionary Measures

Age

2x increase from childhood to 60 years old

Age-specific reference values

Position on blood extraction -seated vs. supine

Up to 30% increase in seated position in plasma NMN and MN

30 min rest before blood extraction

High amine-rich diet

Increase in urine NMN

2x increase in MTY

Avoid beer, wine, cheese, bananas, pineapple, nuts and cereals for 24 hours

Renal Impairment

<4x increase in plasma NMN

<2x increase in MN

MN less affected

Correlate with other parameters

Essential hypertension

Up to 50% increase in plasma NMN and MN

Establish reference values

Decompensated congestive heart failure

2x to 4x increase in plasma NMN

Stabilize patient and repeat test

Plasma MN not affected

Stroke/Intracerebaral hemorrhage

>2x increase in plasma NMN

Biochemical test one week after event

OSA

30% increase in urine NMN

Stabilize illness and repeat test

Plasma MN not affected

NMN; normetanephrine, MN; metanephrine, MTY; methoxytyramine, OSA; obstructive sleep apnea. Adapted from Dobri et al. 201475

 

Table 3. Medians and reference intervals (2.5 and 97.5 percentiles) for plasma normetanephrine and metanephrine according to gender and six age groups

 

 

Age (years)

Normetanephrine (nmol/L)

Metanephrine (nmol/L)

 

N

Median

Median

97.5

2.5

Median

97.5

2.5

 

 

 

 

percentile

percentile

 

percentile

percentile

All

Subjects

1226

41.0

0.298

0.706

0.120

0.147

0.325

0.031

Women

679

40.2

0.293

0.710

0.125

0.132*

0.315

0.035

Men

547

41.0

0.302

0.704

0.120

0.170†

0.329

0.030

5-17y

116

13.2

0.248*

0.470

0.048

0.172†

0.333

0.045

18-29y

229

24.7

0.251*

0.588

0.118

0.137*

0.264

0.034

30-39y

232

34.5

0.273*†

0.618

0.126

0.138*

0.304

0.014

40-49y

283

45.0

0.300†

0.687

0.115

0.147*†

0.324

0.031

50-59y

241

53.0

0.362§

0.747

0.136

0.157†

0.375

0.046

>60y

125

65.4

0.355§

1.047

0.137

0.163†

0.358

0.051

Presence of different symbols (*†§) indicates differences (P < 0.005) in normetanephrine or metanephrine between men and women or among different age groups

Adapted from Eisenhofer et al. 2013134

 

Table 4. Diagnostic test performance of plasma metanephrines with different upper cut-offs and models adjusting for age

 

Upper cut-offs (nmol/L)

Test performance

Model

NMN

MN

Sensitivity (%)

Specificity (%)

Fixed – 97.5 percentiles

0.706

0.325

93.9*

88.3*

Age-dependent linear model

Variable

0.325

93.9*

91.2†

Age-dependent curvilinear model

Variable

0.325

93.7*

93.6§

Age-dependent curvilinear model

Variable

0.446

93.6*

96.0¶

Age-adjusted score model

NA

NA

79.5†

99.9#

NMN, normetanephrine; MN, metanephrine; NA, not applicable (based on a score)

Adapted from Eisenhofer et al. 2013134.

 

Table 5. Main actions of catecholamines on the various receptors and their common manifestations in pheochromocytoma

Target organ system

Receptor types

Sympathetic action

Common manifestations in pheochromocytoma

Skin and mucosa

α1, α2

Vasoconstriction, localized secretion of sweat glands

Pallor, diaphoresis

Peripheral vascular

α1, α2, β2

Vasoconstriction α1, α2 Vasodilation β2

Hypertension

Orthostatic hypotension

Brain

α1, D1

Vasoconstriction

Headache

Heart

β1, β2, D1

Increase in heart rate, contractility, automaticity, conduction velocity

Palpitations, tachycardia, angina

Lungs

α1, β2

Pulmonary arteriole vasoconstriction, tracheal and bronchial muscle relaxation

Dyspnea

Gastrointestinal

α1, α2, β2

Decrease gastrointestinal motility and secretion, constricts sphincters increases liver glycogenolysis and gluconeogenesis, increases pancreatic release of insulin and glucagon

Nausea, abdominal pain, constipation, hyperglycemia

Kidneys

β1

Increase renin secretion

Hypertension

Adipocytes

β1, β3

Increase lipolysis

Weight loss

 

Table 6. Dramatic clinical presentations, laboratory and imaging findings and clinical outcome of patients with unsuspecting pheochromocytoma

Parameter

Clinical Features

Age (years)

20's to 40's

Signs and symptoms

Headache, agitations, diaphoresis, nausea, vomiting

Acute coronary syndrome

Severe congestive heart failure

Arrythmia

Laboratory

Elevated creatine kinase

Normal to elevated troponin

Imaging

Normal angiogram

Dyskinesia, hypokinesia, akinesia by 2D Echo

Diffuse myocardial edema by cardiac MRI

Postoperative persistence of myocardial fibrosis

Clinical outcome

Resolution of signs and symptoms after adrenalectomy

Normalized LV function and ejection fraction

Persistent systolic and diastolic impairment

Death

 

Table 7. Anatomic and Functional Imaging of Pheochromocytoma

 

Author/Year

Sensitivity

Specificity

Anatomic Imaging

 

 

 

CT

Cistaro A. et al. (2015)

59%

100%

Timmers HJ et. Al. (2009)

97% for nonmetastatic

38% for nonmetastatic

 

100% for metastatic

-

MRI

Timmers HJ et. al. (2009)

92% for nonmetastatic

 

 

 

58% nonmetastatic

100% for metastatic

-

CT/MRI

Timmers HJ et. al. (2012)

95.7% for nonmetastatic

90.2%

74,4% for metastaatic

-

Fiebrich HB et. al (2009)

67%

-

Functional Imaging

 

 

 

MIBG

Bandopadhyaya GP et. al. (2015)

68%

100%

Timmers HJ et. al. (2012)

75% for nonmetastatic

91.8%

50 % for metastatic

-

Fottner C.et.al (2010)

53%

91%

Fiebrich HB et. al (2009)

65%

-

Timmers HJ et. al. (2009)

78% for 123I-MIBG in nonmetastatic

 

76% for 131I-MIBG or 123I in nonmetastatic

 

92% for nonmetastatic

123I-MIBG, 131I-MIBG or 123I

 

85% metastatic 123I-MIBG

65%131I-MIBG or 123I

-

Ilias I. et. al. (2008)

87.5% for nonmetastatic,

-

88.9% for metastatic

 

(18)F-DOPA PET/CT Scan

 

Bandopadhyaya GP et. Al. (2015)

82%

100%

Cistaro A. et al. (2015)

75%

100%

Timmers HJ et. Al. (2012)

76.8% for nonmetastatic

90.2%

82.5 % for metastatic

-

Fottner C. et.al (2010)

98%

100%

Luster M et. Al. (2010)

100%

88%

Flebrich HB et. Al (2009)

90%

-

Imani F. et. Al (2009)

84.6%

100%

Timmers HJ et. Al. (2009)

78% nonmetastatic

 

77% nonmetastatic

 

97% metastatic

-

Ilias I. et. Al. (2008)

87.5% for nonmetastatic

 

-

 

91.4% for metastatic

 

(68)Ga-DOTANOC PET/CT

Sharma P. et. Al (2014)

90.4%

85%

HED PET/CT

Yamamoto S. et. Al (2012)

91%

100%

 

Trampal C. et. al. (2004)

92%

100%

123I-metaiodobenzylguanidine (MIBG), positron emission tomography (PET)), F-3,4-dihydroxyphenylalanine (F-DOPA), Hydroxyephedrine (HED)

 

Figure 1

Figure 1. Sympathoadrenal cell lineage development to become adrenal and extra-adrenal chromaffin cells through different signaling pathways. BMP-4 has shown to be the major induction factor for maturation of SA progenitor cells. In the presence of transcription factors MASH-1, Phox2a, Phox2b, Hand2, Gata2/3 and Insm1 during the migration of chromaffin cells, they acquire catecholaminergic features and phenotype. Several crosstalk pathways between GC/GR signaling, GR/MAPK pathways, IGF-1, FGF-2, and NGF receptor trkA have been described which is vital for chromaffin survival. GC-signaling is likewise crucial in the induction of adrenaline synthesizing enzyme phenyl ethanolamine-N-methytransferase (PNMT).

 

Figure 2. (A) Synthesis of catecholamines, namely, dopamine, epinephrine (E) and norepinephrine (NE) begins with the uptake of the the amino acid L-tyrosine by adrenomedullary and sympathoneuronal cells Tyrosine is derived form the diet or synthesized from phenylalanine and is converted to 3,4-dihydroxyphenylalanine (DOPA) by tyrosine hydroxylase (TH), the rate limiting step. L-DOPA is decarboxylysed to dopamine, which is actively transported to vesicles where intravesicular enzyme, dopamine-β- hydrolase (DPH) converts it to NE. NE leaks into the cytoplasm where phenyl ethanolamine N-methyltransferase (PNMT), an enzyme exclusive to adrenomedullary cells, converts it to E that is transported back into the vesicles. (B) The enzyme catechol-O-methytransferase (COMT), which is present both extra- and intramedullary is responsible for conversion of DA to methoxytyramine (MT), NE to normetanephrine (NMN), and E to metanephrine (MN). Sympathetic nerves contain the enzyme monoamine oxidase (MAO) which deaminates NE to 3-4-dihydroxyphenylglycol (DHPG). DHPG is methylated by COMT to 3-methoxy-4-hydroxyphenylglycol (MHPG), which is converted by aldehyde dehydrogenase (AD) in the liver to the metabolite vanillylmandelic acid (VMA). These catechol O-methyl metabolites are produced in excess by tumorous chromaffin cells of pheochromocytoma in the adrenal, sympathetic neurons and extraneuronal metastatic lesions. Metanephrines exist in plasma and urine in both free and sulfate-conjugated form. The sulfate-conjugated forms are catalyzed by a specific sulfotransferase is enzyme, sulfotransferase family, cytosolic, 1A phenol-preferring member 3 (SULT1A3), which is found in gastrointestinal tissues. Measurements of urine metanephrines utilize an acid hydrolysis step to convert the sulfate-conjugated metabolites to free forms. Thus, such measurements reflect the total metanephrines.

 

Figure 3

Figure 3. Computed tomography (CT) scan (A) of a 20-year old female, non-obese, nonsmoker with 1-year history of hypertension and highest BP of 180/120. The adrenal mass measures 7.0 x 5.0 cm. Pathology confirmed PHEO with vascular invasion. Pre-operative 2D-echocardiographic study (B) showed dyskinesia of the septum

 

Figure 4. Algorithm for diagnosis of sporadic (A) and syndromic (B) pheochromocytoma.

Algorithm C depicts the imaging modalities for both. Adapted from Martucci & Pacak (2014)* Docardiac MRI if patient is with moderate to severe CV symptoms: dyspnea, orthopnea, chest pain with or without evidence of myocardial injury, such as abnormal ECG, elevated troponin or creatine kinase.

CC BY: Open Access Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/