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1.  Discriminating Pheochromocytomas from Other Adrenal Lesions: The Dilemma of Elevated Catecholamines 
Annals of surgical oncology  2013;20(12):3855-3861.
Screening tests for pheochromocytoma involve measuring levels of catecholamines in the urine or plasma, which have significant false positive rates. We reviewed patients with adrenal masses and elevated levels of catecholamines to determine the value of different preoperative tests in diagnosing pheochromocytomas.
A retrospective chart review identified patients who underwent adrenalectomy between 1997 and 2011 with elevation of urine or serum catecholamines. A database of clinicopathologic factors was created including preoperative urine and plasma metanephrines, normetanephrines, vanillylmandelic acid, and fractionated catecholamines, and tumor dimensions on imaging and pathology.
Seventy patients underwent adrenalectomy due to presence of an adrenal mass and elevation of catecholamines or normetanephrines or metanephrines. Forty-six had pathologically confirmed pheochromocytomas. To improve our ability to discriminate between pheochromocytoma and other pathology, we examined different combinations of clinicopathologic factors and catecholamine levels and found the best test was a scoring system. Points are awarded for a hierarchy of elevated NM, norepinephrine, metanephrines, with additional points received for age <50 and size on imaging >3.3 cm. A score of 2 is suggestive of pheochromocytoma, with a positive predictive value of 86–87%, while a score of 4 is diagnostic with positive predictive value of 100%.
We found that urine/serum normetanephrine levels were the most valuable screening tool, however a score examining the size of adrenal mass on preoperative CT, age, and either plasma or urine norepinephrine, metanephrine and normetanephrine values leads to a higher positive predictive value, making this scoring system superior to individual lab tests.
PMCID: PMC4270467  PMID: 23884753
2.  Measurement of urinary metanephrines to screen for pheochromocytoma in an unselected hospital referral population 
Clinical chemistry  2006;52(11):2060-2064.
Despite the rarity of pheochromocytoma, the dangers of uncontrolled severe hypertension and the very effective surgical treatment of this condition mean that diagnosis is important. Urinary or plasma catecholamines or catecholamine-derivatives are commonly used to screen for pheochromocytomas prior to imaging. This study investigates whether derived measures obtained from 24-hour urinary metanephrine results, patient age and sex can better predict tumors in populations with a low pre-test probability.
This study takes a pragmatic approach by retrospectively studying the outcomes of an unselected population referred for urinary metanephrine testing (1819 patients) to a tertiary hospital laboratory, and investigates the usefulness of some simple derivative measures for detecting pheochromocytoma. Urinary 24-hour excretion of metanephrine, normetanephrine and 3-methoxytyramine were normalized by dividing by an age- and sex- specific reference range. The ability of products of these normalized measures to predict pheochromocytomas was assessed, compared to a gold standard of biopsy-confirmed tumor.
The normalized product of urinary metanephrine and normetanephrine excretion (nMAD.nNMT) proved to be a highly sensitive (100%) and specific (99.1%) measure yielding a positive predictive value 82%. Receiver-operator characteristic curves were not improved by including the normalized 3-methoxytyramine concentrations in the product. nMAD.nNMT gave higher sensitivity and specificity than either test alone.
We suggest that nMAD.nNMT is a useful measure for identifying pheochromocytoma in a population with a low pre-test probability.
PMCID: PMC2640466  PMID: 16990424
Pheochromocytoma; urinary metanephrines
3.  A systematic review of the literature examining the diagnostic efficacy of measurement of fractionated plasma free metanephrines in the biochemical diagnosis of pheochromocytoma 
Fractionated plasma metanephrine measurements are commonly used in biochemical testing in search of pheochromocytoma.
We aimed to critically appraise the diagnostic efficacy of fractionated plasma free metanephrine measurements in detecting pheochromocytoma. Nine electronic databases, meeting abstracts, and the Science Citation Index were searched and supplemented with previously unpublished data. Methodologic and reporting quality was independently assessed by two endocrinologists using a checklist developed by the Standards for Reporting of Diagnostic Studies Accuracy Group and data were independently abstracted.
Limitations in methodologic quality were noted in all studies. In all subjects (including those with genetic predisposition): the sensitivities for detection of pheochromocytoma were 96%–100% (95% CI ranged from 82% to 100%), whereas the specificities were 85%–100% (95% CI ranged from 78% to 100%). Statistical heterogeneity was noted upon pooling positive likelihood ratios when those with predisposition to disease were included (p < 0.001). However, upon pooling the positive or negative likelihood ratios for patients with sporadic pheochromocytoma (n = 191) or those at risk for sporadic pheochromocytoma (n = 718), no statistical heterogeneity was noted (p = 0.4). For sporadic subjects, the pooled positive likelihood ratio was 5.77 (95% CI = 4.90, 6.81) and the pooled negative likelihood ratio was 0.02 (95% CI = 0.01, 0.07).
Negative plasma fractionated free metanephrine measurements are effective in ruling out pheochromocytoma. However, a positive test result only moderately increases suspicion of disease, particularly when screening for sporadic pheochromocytoma.
PMCID: PMC459231  PMID: 15225350
4.  The role of urinary fractionated metanephrines in the diagnosis of phaeochromocytoma 
Background & objectives:
Plasma and urinary metanephrines are used as screening tests for the diagnosis of phaeochromocytoma. The recommended cut-off levels are not standardized. This study was conducted to identify a cut-off level for 24 h urinary fractionated metanephrines viz. metanephrine (uMN) and normetanephrine (uNMN) using enzyme immunoassay for the diagnosis of phaeochromocytoma.
Consecutive patients suspected to have phaeochromocytoma were included in the study. uMN and uNMN in 24 h urinary sample were measured using a commercial ELISA kit.
Overall, 72 patients were included over a period of 18 months. Twenty patients had histopathologically confirmed phaeochromocytoma and in 52 patients phaeochromocytoma was ruled out. Using the upper limit of normal stated by the assay manufacturer as the cut-off, uMN >350 μg/day had a low sensitivity and uNMN >600 μg/day had a poor specificity. By increasing the cut-off value of uNMN to twice the upper limit, specificity increased significantly without much loss in sensitivity. Combining uMN and uNMN using a cut-off twice the upper limit improved the diagnostic performance - sensitivity (95%); specificity (92.3%); positive predictive value (PPV - 82.6%); negative predictive value (NPV - 98%). In subsets of patients with a variable pretest probability for phaeochromocytoma, the PPV correlates well with the occurred of these tumors decreased, while the NPV remained at 100 per cent.
Interpretation & conclusions:
ELISA is a simple and reliable method for measuring uMN and uNMN. The test has a good NPV and can be used as an initial screening test for ruling out phaeochromocytoma. Each hospital will have to define the cut-off value for the assay being used, choosing a proper control population.
PMCID: PMC3657855  PMID: 23563375
Adrenal tumour; catecholamines; ELISA; metanephrines; phaeochromocytoma
5.  Updated and New Perspectives on Diagnosis, Prognosis, and Therapy of Malignant Pheochromocytoma/Paraganglioma 
Journal of Oncology  2012;2012:872713.
Malignant pheochromocytomas/paragangliomas are rare tumors with a poor prognosis. Malignancy is diagnosed by the development of metastases as evidenced by recurrences in sites normally devoid of chromaffin tissue. Histopathological, biochemical, molecular and genetic markers offer only information on potential risk of metastatic spread. Large size, extraadrenal location, dopamine secretion, SDHB mutations, a PASS score higher than 6, a high Ki-67 index are indexes for potential malignancy. Metastases can be present at first diagnosis or occur years after primary surgery. Measurement of plasma and/or urinary metanephrine, normetanephrine and metoxytyramine are recommended for biochemical diagnosis. Anatomical and functional imaging using different radionuclides are necessary for localization of tumor and metastases. Metastatic pheochromocytomas/paragangliomas is incurable. When possible, surgical debulking of primary tumor is recommended as well as surgical or radiosurgical removal of metastases. I-131-MIBG radiotherapy is the treatment of choice although results are limited. Chemotherapy is reserved to more advanced disease stages. Recent genetic studies have highlighted the main pathways involved in pheochromocytomas/paragangliomas pathogenesis thus suggesting the use of targeted therapy which, nevertheless, has still to be validated. Large cooperative studies on tissue specimens and clinical trials in large cohorts of patients are necessary to achieve better therapeutic tools and improve patient prognosis.
PMCID: PMC3407645  PMID: 22851969
6.  Measurements of Plasma Methoxytyramine, Normetanephrine and Metanephrine as Discriminators of Different Hereditary forms of Pheochromocytoma 
Clinical chemistry  2011;57(3):411-420.
Pheochromocytomas are rare catecholamine–producing tumors derived in at least 30% of cases from mutations in 9 tumor-susceptibility genes identified to date. Testing of multiple genes at considerable expense is often undertaken before a mutation is detected. This study assessed whether measurements of plasma metanephrine, normetanephrine and methoxytyramine, the O-methylated metabolites of catecholamines, might help distinguish different hereditary forms of the tumor.
Plasma concentrations of O-methylated metabolites were measured by liquid chromatography with electrochemical detection in 173 patients with pheochromocytoma, including 38 with multiple endocrine neoplasia type 2 (MEN 2), 10 with neurofibromatosis type 1 (NF1), 66 with von Hippel-Lindau (VHL) syndrome and 59 with mutations of succinate dehydrogenase (SDH) type B or D genes.
In contrast to patients with VHL and SDH mutations, all patients with MEN 2 and NF1 presented with tumors characterized by increased plasma concentrations of metanephrine (indicating epinephrine production). VHL patients usually showed solitary increases in normetanephrine (indicating norepinephrine production), whereas additional or solitary increases in methoxytyramine (indicating dopamine production) characterized 70% of patients with SDH mutations. Patients with NF1 and MEN 2 could be discriminated from those with VHL and SDH mutations in 99% of cases by the combination of normetanephrine and metanephrine. Measurements of plasma methoxytyramine discriminated patients with SDH mutations from those with VHL mutations in a further 78% of cases.
The distinct patterns of plasma catecholamine O-methylated metabolites in patients with hereditary pheochromocytoma provide an easily utilized tool to guide cost-effective genotyping of underlying disease-causing mutations.
PMCID: PMC3164998  PMID: 21262951
pheochromocytoma; paraganglioma; norepinephrine; epinephrine; dopamine; normetanephrine; metanephrine; methoxytyramine; von Hippel-Lindau syndrome; neurofibromatosis type 1; multiple endocrine neoplasia type 2; succinate dehydrogenase
Endocrine regulations  2011;45(2):65-90.
The WHO classification of endocrine tumors defines pheochromocytoma as a tumor arising from chromaffin cells in the adrenal medulla — an intra-adrenal paraganglioma. Closely related tumors of extra-adrenal sympathetic and parasympathetic paraganglia are classified as extra-adrenal paragangliomas. Almost all pheochromocytomas and paragangliomas produce catecholamines. The concentrations of catecholamines in pheochromocytoma tissues are enormous, potentially creating a volcano that can erupt at any time. Significant eruptions result in catecholamine storms called “attacks” or “spells”. Acute catecholamine crisis can strike unexpectedly, leaving traumatic memories of acute medical disaster that champions any intensive care unit. A very well-defined genotype-biochemical phenotype relationship exists, guiding proper and cost-effective genetic testing of patients with these tumors. Currently, the production of norepinephrine and epinephrine is optimally assessed by the measurement of their O-methylated metabolites, normetanephrine or metanephrine, respectively. Dopamine is a minor component, but some paragangliomas produce only this catecholamine or this together with norepinephrine. Methoxytyramine, the O-methylated metabolite of dopamine, is the best biochemical marker of these tumors. In those patients with equivocal biochemical results, a modified clonidine suppression test coupled with the measurement of plasma normetanephrine has recently been introduced. In addition to differences in catecholamine enzyme expression, the presence of either constitutive or regulated secretory pathways contributes further to the very unique mutation-dependent catecholamine production and release, resulting in various clinical presentations.
Oxidative stress results from a significant imbalance between levels of prooxidants, generated during oxidative phosphorylation, and antioxidants. The gradual accumulation of prooxidants due to metabolic oxidative stress results in proto-oncogene activation, tumor suppressor gene inactivation, DNA damage, and genomic instability. Since the mitochondria serves as the main source of prooxidants, any mitochondrial impairment leads to severe oxidative stress, a major outcome of which is tumor development. In terms of cancer pathogenesis, pheochromocytomas and paragangliomas represent tumors where the oxidative phosphorylation defect due to the mutation of succinate dehydrogenase is the cause, not a consequence, of tumor development. Any succinate dehydrogenase pathogenic mutation results in the shift from oxidative phosphorylation to aerobic glycolysis in the cytoplasm (also called anaerobic glycolysis if hypoxia is the main cause of such a shift). This phenomenon, also called the Warburg effect, is well demonstrated by a positive [18F]-fluorodeoxyglycose positron emission tomography scan. Microarray studies, genome-wide association studies, proteomics and protein arrays, metabolomics, transcriptomics, and bioinformatics approaches will remain powerful tools to further uncover the pathogenesis of these tumors and their unique markers, with the ultimate goal to introduce new therapeutic options for those with metastatic or malignant pheochromocytoma and paraganglioma. Soon oxidative stress will be tightly linked to a multistep cancer process in which the mutation of various genes (perhaps in a logistic way) ultimately results in uncontrolled growth, proliferation, and metastatic potential of practically any cell. Targeting the mTORC, IGF-1, HIF and other pathways, topoisomerases, protein degradation by proteosomes, balancing the activity of protein kinases and phosphatases or even synchronizing the cell cycle before any exposure to any kind of therapy will soon become a reality. Facing such a reality today will favor our chances to “beat” this disease tomorrow.
PMCID: PMC3414427  PMID: 21615192
Pheochromocytoma; Paraganglioma; Catecholamines; Metanephrines; Mitochondria; Oxidative Phosphorylation; Glycolysis
8.  A Rare Case of Adrenal Pheochromocytoma with Unusual Clinical and Biochemical Presentation: 
A Case Report and Literature Review 
Oman Medical Journal  2015;30(5):382-390.
A 50-year-old Omani woman presented to the Outpatient Clinic, Royal Hospital, Oman with right upper abdominal pain and backache that had lasted 10 days. She had no palpitation, sweating, or hypertension (blood pressure 122/78mmHg). The patient’s history revealed that she had a similar incidence of abdominal pain two months prior, which was a "dull ache" in nature and somewhat associated with headache. The pain was relieved using a mild analgesic drug. Abdominal ultrasonography showed a right adrenal mass, and both computed tomography and magnetic resonance imaging of the adrenal glands confirmed a right adrenal mass consistent with adrenal pheochromocytoma. However, clinical biochemistry tests revealed normal levels of plasma catecholamines (dopamine, norepinephrine, and epinephrine) and metanephrine, which are unusual findings in adrenal pheochromocytoma. Meanwhile, the patient had markedly raised plasma normetanephrine (10-fold) which, together with the normal metanephrine, constitutes a metabolic profile that is compatible with extra-adrenal pheochromocytoma. The patient also had markedly raised chromogranin A (16-fold), consistent with the presence of a neuroendocrine tumor. Laparoscopic right adrenalectomy was done and the adrenal tumor was excised and retrieved in total. Histopathology and immunohistochemistry confirmed the diagnosis of adrenal pheochromocytoma; the tumor cells being positive for chromogranin, synaptophysin, and S-100 protein. Following surgery, the patient did well and showed full recovery at follow-up after three months. Molecular genetic testing showed no pathogenic mutation in pheochromocytoma genes: MAX, SDHA, SDHAF2, SDHB, SDHC, SDHD, VHL, and PRKAR1A. A review of the literature was conducted to identify the pathophysiology and any previous reports of such case. To our knowledge, this is the first report in Oman of the extremely rare entity of pheochromocytoma with an unusual clinical and biochemical scenario.
PMCID: PMC4576385  PMID: 26421121
Adrenal glands; Adrenalectomy; Catecholamines; Chromogranin A; Metanephrine; Normetanephrine; Pheochromocytoma
9.  Development and Validation of Liquid Chromatography-Tandem Mass Spectrometry Method for Quantification of Plasma Metanephrines for Differential Diagnosis of Adrenal Incidentaloma 
Annals of Laboratory Medicine  2015;35(5):519-522.
High-resolution imaging techniques have increased the detection rate of adrenal incidentaloma. We developed a method of liquid chromatography-tandem mass spectrometry (LC-MS/MS) for detection of plasma free metanephrine (MN) and normetanephrine (NMN) and evaluated its analytical performance and clinical efficacy in differential diagnosis of adrenal incidentaloma. After solid-phase extraction, chromatographic isolation of the analytes and internal standard was achieved by column elution in the LC-MS/MS system. The analytes were detected in multiple-reaction monitoring mode by using positive electrospray ionization: MN, transition m/z 180.1→165.1; NMN, m/z 166.1→134.1. This method was validated for linearity, precision, accuracy, lower limits of quantification and detection, extraction recovery, and the matrix effect. Plasma concentrations of MN and NMN of 14 patients with pheochromocytoma were compared with those of 17 healthy volunteers, 10 patients with essential hypertension, and 60 patients with adrenal adenoma. The assay's linear range was 0.04-50.0 and 0.08-100.0 nmol/L for MN and NMN, respectively. Assay imprecision was 1.86-7.50%. The accuracy ranged from -7.50% to 2.00%, and the mean recovery of MN and NMN was within the range 71.5-95.2%. Our LC-MS/MS method is rapid, accurate, and reliable and useful for differential diagnosis of adrenal incidentaloma.
PMCID: PMC4510505  PMID: 26206689
Metanephrines; Plasma; Mass spectrometry; Validation; Pheochromocytoma
10.  Plasma free versus deconjugated metanephrines for diagnosis of phaeochromocytoma 
Clinical endocrinology  2013;79(4):10.1111/cen.12191.
Diagnosis of phaeochromocytoma is commonly performed by measurements of plasma free normetanephrine and metanephrine. Plasma deconjugated normetanephrine and metanephrine have been proposed as alternative equivalent, but easier to measure biomarkers.
The aim of this study was to compare the diagnostic performances of plasma free versus deconjugated normetanephrine and metanephrine in patients tested for phaeochromocytoma.
The study population included a reference group of 262 normotensive and hypertensive volunteers, 198 patients with phaeochromocytoma and 528 patients initially suspected of having the tumour, but with negative investigations after at least 2 years of follow up. Measurements were performed using liquid chromatography with electrochemical detection.
Median plasma concentrations of free normetanephrine were 17-fold higher in patients with phaeochromocytoma than in the reference population, a 72% larger (p<0.001) difference than that for the 10-fold higher levels of plasma deconjugated normetanephrine. In contrast, relative increases of plasma concentrations of free and deconjugated metanephrine were similar. Using upper cut-offs established in the reference population, measurements of plasma free metabolites provided superior diagnostic performance than deconjugated metabolites according to measures of both sensitivity (97% vs 92%, p=0.002) and specificity (93 vs 89%, p=0.012). The area under the receiver operating characteristic curve for the free metabolites was larger than that for the deconjugated metabolites (0.986 vs 0.965, p<0.001).
Measurements of plasma free normetanephrine and metanephrine are superior to the deconjugated metabolites for diagnosis of phaeochromocytoma.
PMCID: PMC3762922  PMID: 23461656
Phaeochromocytoma; diagnostic tests; free metanephrines; deconjugated metanephrines; normetanephrine; metanephrine
11.  Advances in Biochemical Screening for Phaeochromocytoma using Biogenic Amines 
Biochemical testing for phaeochromocytoma is performed in diagnostic laboratories using a variety of tests with plasma, serum or 24-hour urine collections. These tests include catecholamines and their methylated metabolites - the metanephrines, either individually or in combination with their sulfated metabolites. High-performance liquid chromatography (HPLC) continues to be the dominant analytical method for biogenic amine quantitation. Chromatographic techniques are changing, with improvements in sample preparation procedures, column technology and more specific analyte detection using tandem mass spectrometry. Enrolments in quality assurance programs indicate that there are still many more laboratories in Australasia analysing urinary catecholamines than metanephrines. Nevertheless, clinical evidence and expert opinion favour metanephrines as the analytes with highest sensitivity for the detection of phaeochromocytoma. Practical issues such as better chemical stability and easier specimen collection also favour metanephrines over catecholamines. For these reasons, it is likely that laboratories increasingly will replace urine catecholamine testing with either plasma or urine metanephrines. However in interpreting positive results, the need remains to consider issues such as pre-test probability and use of potentially interfering medications.
PMCID: PMC2643090  PMID: 19224007
12.  Plasma free metanephrine, normetanephrine, and 3-methoxytyramine for the diagnosis of pheochromocytoma/paraganglioma 
Pheochromocytomas (PHEO) and paragangliomas (PGL) are derived from paraganglia of the sympathetic and parasympathetic nervous system. Most of the sympathetic PHEO/PGL secrete either catecholamine or their metabolites, metanephrines, whereas parasympathetic PHEO/PGL are nonsecretory. We assessed the utility of plasma free 3-methoxytyramine (3MT), normetanephrine (NM), and metanephrine (MN) for the diagnosis of PHEO/PGL.
Materials and Methods:
Sixty-five patients referred to endocrine/ENT clinics were enrolled. Twelve patients with von Hippel-Lindau (VHL), neurofibromatosis type 1 (NF1) and multiple endocrine neoplasia type 2 (MEN2) syndromes were excluded. Remaining 53 patients (39 patients with adrenal, abdominal, cervical and thoracic PHEO/PGL and 14 patients with head and neck PGL (HNPGL) were taken for this study. Sixty-five age- and sex-matched subjects were taken as controls. Plasma levels 3MT, NM, and MN were measured using high-performance liquid chromatography. Receivers operating characteristics was plotted and cut-off levels were established.
When compared with controls, there was a 36-, 8.7- and 9.5-fold increase in levels of NM, 3MT and MN in the patients with PHEO/PGL and 7.2- and 2.7-fold increase in 3MT and NM, in the patients with HNPGL, respectively. In malignant PHEO/PGL, there was a 99-, 16- and 20-fold increase and in benign PHEO/PGL, there was 19-, 6.8- and 6.4-fold increase in levels of NM, 3MT, and MN, respectively. NM in combination with MN was high in 97% of the patients with PHEO/PGL. All three metabolites in combination were high in 83% of patients with HNPGL. In malignant PHEO/PGL, 50% subjects had increased levels of both NM and 3MT.
Measurement of plasma-free NM along with 3MT and MN provides a better tool for the diagnosis of PHEO/PGL as well as HNPGL. Further, NM in combination with 3MT can be used for the diagnosis of malignant PHEO/PGL.
PMCID: PMC4566344  PMID: 26425473
3 methoxy tyramine; metanephrine; normetanephrine; paraganglioma; pheochromocytoma
13.  Pheochromocytoma associated with neurofibromatosis type 1: concepts and current trends 
Neurofibromatosis Type 1(NF-1) has autosomal dominant inheritance with complete penetrance, variable expression and a high rate of new mutation. Pheochromocytoma occurs in 0.1%-5.7% of patients with NF-1.
Case presentation
We present the case of a 37-year-old patient with laparoscopically resected pheochromocytoma. He was investigated for hypertension, flushing and ectopic heart beat. Abdominal CT and MRI revealed a mass measuring 8 × 4 cm in the right adrenal gland. The diagnosis of pheochromocytoma was confirmed by elevated 24-hour urine levels of VMA, metanephrines and catecholamines as well as positive MIBG scan. The patient presented with classic clinical features of NF-1, which was confirmed by pathologic evaluation of an excised skin nodule. The patient underwent laparoscopic right adrenalectomy through a transabdominal approach and was discharged on the second postoperative day, being normotensive. The patient is normotensive without antihypertensive therapy 11 years after the procedure.
Nowadays in the era of laparoscopy, patients with pheochromocytoma reach the operating theatre easier than in the past. Despite, the feasibility and oncological efficacy of the laparoscopic approach to the adrenals, continued long term follow-up is needed to establish the minimally invasive technique as the preferred approach. Furthermore, these patients should be further investigated for other neoplasias and stigmata of other neurocutaneous syndromes, taking into account the association of the familial pheochromo-cytoma with other familial basis inherited diseases.
PMCID: PMC2848134  PMID: 20219130
14.  Brown Adipose Tissue in Humans Is Activated by Elevated Plasma Catecholamines Levels and Is Inversely Related to Central Obesity 
PLoS ONE  2011;6(6):e21006.
Recent studies have shown that adult human possess active brown adipose tissue (BAT), which might be important in controlling obesity. It is known that ß-adrenoceptor-UCP1 system regulates BAT in rodent, but its influence in adult humans remains to be shown. The present study is to determine whether BAT activity can be independently stimulated by elevated catecholamines levels in adult human, and whether it is associated with their adiposity.
Methodology/Principal Findings
We studied 14 patients with pheochromocytoma and 14 normal subjects who had performed both 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) and plasma total metanephrine (TMN) measurements during 2007–2010. The BAT detection rate and the mean BAT activity were significantly higher in patients with elevated TMN levels (Group A: 6/8 and 6.7±2.1 SUVmean· g/ml) than patients with normal TMN concentrations (Group B: 0/6 and 0.4±0.04 SUVmean· g/ml) and normal subjects (Group C: 0/14 and 0.4±0.03 SUVmean·g/ml). BAT activities were positively correlated with TMN levels (R = 0.83, p<0.0001) and were inversely related to body mass index (R = −0.47, p = 0.010), visceral fat areas (R = −0.39, p = 0.044), visceral/total fat areas (R = −0.52, p = 0.0043) and waist circumferences (R = −0.43, p = 0.019). Robust regression revealed that TMN (R = 0.81, p<0.0001) and waist circumferences (R = −0.009, p = 0.009) were the two independent predictors of BAT activities.
Brown adipose tissue activity in adult human can be activated by elevated plasma TMN levels, such as in the case of patients with pheochromocytoma, and is negatively associated with central adiposity.
PMCID: PMC3118816  PMID: 21701596
15.  A rare case of juvenile hypertension: coexistence of type 2 multiple endocrine neoplasia -related bilateral pheochromocytoma and reninoma in a young patient with ACE gene polymorphism 
Pheochromocytoma and reninoma represent two rare diseases causing hypertension. We here reported a rare case of association between type 2 multiple endocrine neoplasia related bilateral pheochromocytoma and reninoma. Moreover, polymorphism of ACE gene, which is known to be related to an increase of cardiovascular risk, has been found in the same patient.
Case presentation
A 24 year old Caucasian man came to our attention for severe hypertension, resistant to anti-hypertensive polytherapy. At the age of twenty he had undergone total thyroidectomy with lymphadenectomy for medullary carcinoma. Genetic testing showed a RET mutation of codon 918 (exon 16) not documented in other family members. During the follow-up, a progressive increase of urinary metanephrines and catecholamines was recorded. Our evaluation confirmed the presence of severe hypertension (220/140 mmHg) and a severe increase of urinary catecholamines and metanephrines. Due to the presence of hypokalemia, other causes of hypertension were researched leading to the discovery of hyperreninemia (236 μUI/ml) with mild hyperaldosteronism, and a mild increase of the renal artery resistance at ultrasound. An abdominal MRI showed multiple adrenal masses and a right kidney nodular lesion of about 2 cm.
The patient underwent bilateral adrenalectomy and right nephrectomy, and histology confirmed the presence of bilateral pheochromocytoma and right reninoma. The post-surgery laboratory evaluation showed a rapid reduction of the urinary metanephrines while plasma renin level remained low in spite of the bilateral adrenalectomy without any mineralocorticoid supplementation. To further investigate these unusual feature, we performed genetic testing for the ACE gene, which revealed the presence of ACE I/D polymorphism.
This unique report describes the association between two rare causes of hypertension in the same patient. Furthermore, the absence of requirement of mineralocorticoid supplementation in spite of bilateral adrenalectomy, represent an uncommon and interest finding.
PMCID: PMC4472263  PMID: 26084817
Pheochromocytoma; Reninoma; MEN2B; ACE polymorphism; Hypertension
16.  An Adrenal Mass and Increased Catecholamines: Monoamine Oxidase or Pheochromocytoma Effect? 
Hormonal evaluation in patients with an adrenal incidentaloma can be difficult in patients with comorbidities or in patients using interfering drugs. We present a case of a 54-year-old man who was evaluated for an adrenal mass. The medical history reported treatment with a monoamine oxidase (MAO) inhibitor for recurrent psychoses. Hormonal screening showed elevated levels of normetanephrine and metanephrine in plasma and urine, suggesting a diagnosis of pheochromocytoma (PHEO), and an adrenalectomy was performed. Histologic examination showed that the tumor had an origin of the adrenal cortex. MAO inhibitors are also known to cause elevated levels of catecholamines. In this case, a PHEO seemed more likely the cause due to repeatedly elevated levels of metanephrines and normal levels of catecholamines. Since the tumor had an origin of the adrenal cortex, the use of MAO inhibitors was the most likely explanation for the elevated levels of metanephrines. This case illustrated the difficulties in diagnosing PHEO, especially in patients with comorbidities and interfering drugs.
PMCID: PMC4285070  PMID: 25584109
Pheochromocytoma; MAO inhibitor; Pseudopheochromocytoma; Hormonal screening
17.  Use of 6-[18F]-fluorodopamine positron emission tomography as first-line investigation for the diagnosis and localization of non-metastatic and metastatic pheochromocytoma 
Clinical endocrinology  2008;71(1):11-17.
Imaging modalities available for the localization of pheochromocytoma (PHEO) include computed tomography (CT), magnetic resonance imaging (MRI), [123I]-or [131I]-labeled metaiodobenzylguanidine (123/131I-MIBG) scintigraphy and 6-[18F]-fluorodopamine (18F-FDA) positron emission tomography (PET). Our aim was to investigate the yield of 18F-FDA PET versus biochemical testing and other imaging techniques to establish the diagnosis and location of PHEO.
Patients and measurements
The study included 99 consecutive patients (35 M, 64 F, mean±SD age 46.4±13.4 years), who underwent 18F-FDA PET, biochemical testing (plasma catecholamines and free metanephrines) and CT and/or MRI. The majority (78%) also underwent 123/131I-MIBG.
26 patients had non-metastatic PHEO, 34 patients had metastatic PHEO, and PHEO was ruled out in 39 patients. Investigations to rule out or confirm PHEO yielded the following sensitivity/specificity: plasma metanephrines 97/95%, 18F-FDA 92/90%, 123I-MIBG 83/100%, 123/131I-MIBG 70/100%, CT 100/41%, MRI 98/60%. Sensitivities for localizing non-metastatic PHEO on a per-lesion base were: CT 97%, MRI 92%, 18F-FDA 78%, 123I-MIBG 78% and 123/131I-MIBG 76%. Sensitivities for detecting metastases on a per-patient base were: CT and MRI 100%, 18F-FDA 97%, 123I-MIBG 85%, and 123/131I-MIBG 65%.
For tumor localization, 18F-FDA PET and 123/131I-MIBG scintigraphy perform equally well in patients with non-metastatic PHEO, but metastases are better detected by 18FFDA PET than by 123/131I-MIBG.
PMCID: PMC2713382  PMID: 19138315
paraganglioma; positron emission tomography; imaging; fluorodopamine; metanephrines
18.  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;19(1):83-93.
The purpose of this study was to present the characteristics and outcome of patients with proven pheochromocytoma or paraganglioma who had false-negative 123I-MIBG SPECT.
Twenty one patients with false-negative 123I-MIBG SPECT, (6 males, 15 females) aged 13–55 years (mean 40.9 years) were included. We classified them according to the stage of the disease as non-metastatic or metastatic at the time of false-negative 123I-MIBG SPECT study, the location and size of the tumor, plasma and urinary catecholamine and metanephrine levels, genetic mutations, and outcome in terms of occurrence and progression of metastases and death.
Thirteen patients were evaluated for metastatic tumors while 8 others were seen for non-metastatic disease. All primary tumors and multiple metastatic foci did not show avid 123I-MIBG uptake regardless of the tumor diameter. The majority of patients had extra-adrenal tumors with hypersecretion of normetanephrine or norepinephrine. SDHB mutation was present in 52% (n=11) of cases, RET mutation in 4% (n=1), and the rest were apparently sporadic. Twenty four percent (n=5) had metastatic disease on initial presentation. Fourteen patients were followed-up for 3–7 years. From them, 71% (n=10) had metastatic disease and majority had SDHB mutation. Nine are still alive while 5 (4 were SDHB) died due to metastatic disease.
A false-negative 123I-MIBG SPECT is frequently related to metastatic tumors and usually due to SDHB mutations with unfavourable prognosis. We, therefore, recommend that patients with false-negative 123I-MIBG SPECT be tested for SDHB mutations and to undergo more regular and close follow-up.
PMCID: PMC3420013  PMID: 22167067
123I-MIBG; pheochromocytoma; paraganglioma; succinate dehydrogenase subunit B; catecholamines; metanephrines
19.  Restoration of Self-Awareness of Hypoglycemia in Adults With Long-Standing Type 1 Diabetes 
Diabetes Care  2013;36(12):4063-4070.
Impaired awareness of hypoglycemia (IAH) and defective counterregulation significantly increase severe hypoglycemia risk in type 1 diabetes (T1D). We evaluated restoration of IAH/defective counterregulation by a treatment strategy targeted at hypoglycemia avoidance in adults with T1D with IAH (Gold score ≥4) participating in the U.K.-based multicenter HypoCOMPaSS randomized controlled trial.
Eighteen subjects with T1D and IAH (mean ± SD age 50 ± 9 years, T1D duration 35 ± 10 years, HbA1c 8.1 ± 1.0% [65 ± 10.9 mmol/mol]) underwent stepped hyperinsulinemic-hypoglycemic clamp studies before and after a 6-month intervention. The intervention comprised the HypoCOMPaSS education tool in all and randomized allocation, in a 2 × 2 factorial study design, to multiple daily insulin analog injections or continuous subcutaneous insulin infusion therapy and conventional glucose monitoring or real-time continuous glucose monitoring. Symptoms, cognitive function, and counterregulatory hormones were measured at each glucose plateau (5.0, 3.8, 3.4, 2.8, and 2.4 mmol/L), with each step lasting 40 min with subjects kept blinded to their actual glucose value throughout clamp studies.
After intervention, glucose concentrations at which subjects first felt hypoglycemic increased (mean ± SE from 2.6 ± 0.1 to 3.1 ± 0.2 mmol/L, P = 0.02), and symptom and plasma metanephrine responses to hypoglycemia were higher (median area under curve for symptoms, 580 [interquartile range {IQR} 420–780] vs. 710 [460–1,260], P = 0.02; metanephrine, 2,412 [−3,026 to 7,279] vs. 5,180 [−771 to 11,513], P = 0.01). Glycemic threshold for deterioration of cognitive function measured by four-choice reaction time was unchanged, while the color-word Stroop test showed a degree of adaptation.
Even in long-standing T1D, IAH and defective counterregulation may be improved by a clinical strategy aimed at hypoglycemia avoidance.
PMCID: PMC3836150  PMID: 24130355
20.  Pheochromocytoma presenting with arterial and intracardiac thrombus in a 47-year-old woman: a case report 
Pheochromocytoma is a rare cause of hypertension but it could have severe consequences if not recognized and treated appropriately. The association of pheochromocytoma and thrombosis is even rarer but significantly increases management complexity, morbidity and mortality. To the best of our knowledge, this is the first report of a patient with pheochromocytoma presenting with left axillary arterial and intracardiac thrombus.
Case presentation
A 47-year-old Caucasian woman with a past medical history of hypertension presented for medical attention with left arm numbness. Doppler ultrasound showed an obstructing thrombus in her left axillary artery. She had symptom resolution after stent placement in her left axillary artery. A subsequent echocardiogram demonstrated a large intracardiac mass and abdominal computed tomography revealed a 7 cm mass between her spleen and left kidney. Labile blood pressure was noted during admission and she had very high levels of plasma and 24-hour urine catecholamines and metanephrines tests. A (123)I- metaiodobenzylguanidine scan showed intense uptake in the left abdominal mass. After adequate alpha blockage with phenoxybenzamine, laparoscopic tumor resection was performed without complications. She had normal metanephrines and complete symptom resolution afterwards. The intracardiac mass also disappeared with anticoagulation. All other endocrine laboratory abnormalities returned to normal after surgery.
Arterial and ventricular thrombosis occurring in patients with pheochromocytoma is rare. A multi-disciplinary approach is necessary in caring for this type of patient. Catecholamines likely contributed to the development of thrombosis in our patient. Early recognition of pheochromocytoma is the key to improving outcome.
PMCID: PMC3152527  PMID: 21752274
21.  Genetic Screening for von Hippel-Lindau Gene Mutations in Non-syndromic Pheochromocytoma: Low Prevalence and False-positives or Misdiagnosis Indicate a Need for Caution 
Genetic testing of tumor susceptibility genes is now recommended in most patients with pheochromocytoma or paraganglioma (PPGL), even in the absence of a syndromic presentation. Once a mutation is diagnosed there is rarely follow-up validation to assess the possibility of misdiagnosis. This study prospectively examined the prevalence of von Hippel-Lindau (VHL) gene mutations among 182 patients with non-syndromic PPGLs. Follow-up in positive cases included comparisons of biochemical and tumor gene expression data in 64 established VHL patients, with confirmatory genetic testing in cases with an atypical presentation. VHL mutations were detected by certified laboratory testing in 3 of the 182 patients with non-syndromic PPGLs. Two of the 3 had an unusual presentation of diffuse peritoneal metastases and substantial increases in plasma metanephrine, the metabolite of epinephrine. Tumor gene expression profiles in these 2 patients also differed markedly from those associated with established VHL syndrome. One patient was diagnosed with a partial deletion by Southern blot analysis and the other with a splice site mutation. Quantitative polymerase chain reaction, multiplex ligation-dependent probe amplification, and comparative genomic hybridization failed to confirm the partial deletion indicated by certified laboratory testing. Analysis of tumor DNA in the other patient with a splice site alteration indicated no loss of heterozygosity or second hit point mutation. In conclusion, VHL germline mutations represent a minor cause of non-syndromic PPGLs and misdiagnoses can occur. Caution should therefore be exercised in interpreting positive genetic test results as the cause of disease in patients with non-syndromic PPGLs.
PMCID: PMC3501345  PMID: 22438210
pheochromocytoma; paraganglioma; von Hippel-Lindau syndrome; mutation testing; germline mutations; loss of heterozygosity
22.  Pheochromocytoma: An Uncommon Presentation of an Asymptomatic and Biochemically Silent Adrenal Incidentaloma 
Pheochromocytomas are rare tumours originating from the chromaffin tissue. The clinical manifestations are variable and are not specific; as a result, pheochromocytomas often imitate other diseases. The diagnosis is usually established by biochemical studies, i.e., the measurement of catecholamines or their metabolites in urine or plasma, followed by radiographic and scintigraphic studies for localisation. Surgical removal of the tumour is the preferred treatment. We report a 30-year-old woman presenting with an adrenal incidentaloma that was 7.6 × 5.3 × 4.8 cm in size on an abdominal computed tomography scan. Investigations for adrenal hormones, including a low-dose dexamethasone suppression test, plasma aldosterone level, 24-hour urinary metanephrine and vanillylmandelic acid levels, and plasma metanephrine level were all within the normal ranges. During the surgical resection, the patient had a hypertensive spell. Surgery was postponed, and the blood pressure was adequately controlled with α blockers, followed by β blockers. After 2 weeks, the surgery was followed by a pathological biopsy that confirmed the pheochromocytoma diagnosis.
PMCID: PMC3431738  PMID: 22973143
adrenal incidentaloma; catecholamines; hypertension; pheochromocytoma; scintigraphy
23.  A case of normotensive pheochromocytoma with management dilemma 
We report an unusual case of normotensive pheochromocytoma detected incidentally, presenting a pre-operative management problem.
Case Note:
A 40-year-old lady with vague abdominal symptoms was initially discovered with a left adrenal incidentaloma by ultrasound abdomen, which was also revealed in computed tomography (CT). After exclusion of all the causes with possible necessary investigations, pheochromocytoma was confirmed with elevated 24 hour urinary metanephrine and normetanephrine. Her blood pressure was in low to normotensive range all throughout. She was attempted to be prepared with combined alpha and beta blockade but could not tolerate this regimen due to symptomatic hypotension. Subsequently, surgical preparation was planned cautiously with alpha-adenergic blockade only. With intensive monitoring, she underwent uneventful left adrenalectomy, and surgical pathology was consistent with pheochromocytoma.
This case illustrates an unusual presentation of normotensive pheochromocytoma as adrenal incidentaloma. Pre-operative preparation in these patients can be achieved with alpha-adrenergic blockade, adequate hydration, and liberal salt intake.
PMCID: PMC3603081  PMID: 23565433
Normotensive pheochromocytoma; adrenal incidentaloma; preoperative preparation
24.  Pheochromocytoma in an 8-year-old patient with Multiple Endocrine Neoplasia Type 2A: Implications for Screening 
Journal of surgical oncology  2013;108(4):203-206.
Multiple endocrine neoplasia type 2 (MEN2) is an autosomal dominant hereditary cancer syndrome caused by mutations in the RET proto-oncogene. In patients with MEN 2A and 2B the penetrance of pheochromocytoma is variable and childhood pheochromocytoma in the setting of MEN 2 remains rare.
Patient and Intervention
We present the case of an 8-year-old female with known MEN 2A, C634Y RET mutation, found to have markedly elevated plasma normetanephrines and total metanephrines, and diagnosed with a 6 cm pheochromocytoma requiring laparoscopic unilateral adrenalectomy.
Given this patient’s age at diagnosis, current screening guidelines should recommend annual screening beginning at age 8 for patients with MEN 2B or for patients with MEN 2A with codons 630 or 634 RET mutations.
PMCID: PMC3983847  PMID: 23868299
Multiple endocrine neoplasia type 2; pheochromocytoma; screening; adrenalectomy
25.  Pheochromocytoma presenting as acute decompensated heart failure reversed with medical therapy 
BMJ Case Reports  2012;2012:bcr2012006319.
A 26-year-old woman presented to hospital with acute chest pain, hypertension, tachycardia and an elevated serum creatinine. She developed respiratory distress requiring endotracheal intubation and mechanical ventilation. She progressed to multiorgan failure due to decompensated congestive heart failure. Echocardiography demonstrated global hypokinesis and an ejection fraction of <10%. Her cardiac function improved with fluid resuscitation and β blockade, and she was eventually discharged home. She was readmitted a few days later with pancreatitis after presenting with nausea, abdominal pain and hypertension. During hospitalisation she had paroxysms of headache, nausea and diaphoresis associated with hypertension and tachycardia. A CT scan of her abdomen revealed an adrenal mass and serum metanephrine studies confirmed the diagnosis of pheochromocytoma. After fluid resuscitation and sympathetic blockade her ejection fraction improved to 55%. The patient underwent an uneventful adrenalectomy and made a complete recovery.
PMCID: PMC4543352  PMID: 22814979

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