Pheochromocytoma: 1926-1993

Pancreas-sparing tumor resection for peripancreatic paraganglioma: a case series of six patients

Paragangliomas (PGLs) located around the pancreas are rare and challenging to diagnose preoperatively. Tumor resection with pancreatectomy is often performed for peripancreatic PGL. However, pancreas-sparing tumor resection can be indicated with an accurate preoperative diagnosis. Six patients with pathologically diagnosed peripancreatic PGL were included. The clinical data were retrospectively collected from medical records. Five of them were suspected of peripancreatic PGL on imaging studies due to the fat plane identified between the tumor and pancreas, and subsequently diagnosed with PGL preoperatively based on elevated urinary catecholamine levels and/or metaiodobenzylguanidine scintigraphy without biopsy. All patients underwent pancreas-sparing tumor resection with negative surgical margins, and they did not develop postoperative complications related to potential damage to the pancreas. A fat plane between the tumor and pancreas on imaging studies and hormone levels are key findings for obtaining an accurate preoperative diagnosis of peripancreatic PGL, which can be managed with pancreas-sparing tumor resection.

Adrenal Mass and Hypokalaemia: The Zebra Among Horses

Pheochromocytoma rarely presents with unexplained hypokalaemia, although there are some case reports in the literature. The mechanism behind this could be the increased cellular potassium uptake promoted by beta-2-adrenoreceptor hyperactivation and insulin resistance. We present the case of a 68-year-old hypertensive female patient with a unilateral adrenal mass discovered on angio-CT and typical signs of adrenergic hyperstimulation (hypertensive crisis, headache, and sweating) associated with multiple arrhythmic episodes but with normal plasma and urinary catecholamine levels. During the work-up for hormonal hypersecretion and the cessation of anti-aldosterone medication, the patient presented resistant hypokalaemia. Due to uncorrectable hypokalaemia, we were unable to perform hormonal investigations for primary hyperaldosteronism and referred the patient for laparoscopic adrenalectomy. The histological diagnosis revealed left pheochromocytoma. Postoperatively, the patient experienced rebound hyperkalaemia. In a patient with a unilateral adrenal mass and hypokalaemia, besides primary hyperaldosteronism and adrenocorticotropic hormone-independent hypercortisolism, a possible pheochromocytoma should be ruled out as well by the clinician before surgery.

Comparison of preoperative alpha-blockade for resection of paraganglioma and pheochromocytoma

OBJECTIVE

Phenoxybenzamine (nonselective, non-competitive alpha-blocker) is the preferred drug for preoperative treatment of pheochromocytoma, but doxazosin (selective, competitive alpha-blocker) may be equally effective. We compared the efficacy of doxazosin versus phenoxybenzamine.

METHODS

We conducted a prospective study of patients undergoing pheochromocytoma or paraganglioma resection by randomizing pretreatment with phenoxybenzamine or doxazosin at a single tertiary referral center. The high cost of phenoxybenzamine led to high crossover to doxazosin. Randomization was halted, and a consecutive historical cohort of phenoxybenzamine patients was included for a case-control study design. The efficacy of alpha-blockade was assessed with pre-induction infusion of incremental doses of phenylephrine. The primary outcomes were mortality, cardiovascular complications, and ICU admission. Secondary outcomes were hemodynamic instability index (proportion of operation outside of hemodynamic goals), adequacy of blockade by phenylephrine titration test, and drug costs.

RESULTS

Twenty-four patients were prospectively enrolled (doxazosin, n=20; phenoxybenzamine, n=4), and 15 historical patients treated with phenoxybenzamine were added (total phenoxybenzamine, n=19). No major cardiovascular complications occurred in either group. The phenylephrine dose-response curves showed less blood pressure rise in the phenoxybenzamine than the doxazosin group (linear regression coefficient 0.008 versus 0.018, P=.01), suggesting better alpha-blockade in the phenoxybenzamine group. Median hemodynamic instability index was 14% versus 13% in the phenoxybenzamine and doxazosin groups, respectively (P=.56). The median highest daily cost of phenoxybenzamine was $442.20 compared to $5.06 for doxazosin.

CONCLUSION

Phenoxybenzamine may blunt intraoperative hypertension better than doxazosin, but this difference did not translate to fewer cardiovascular complications and is offset by a considerably increased cost.

Pheochromocytoma Diagnosed during the Treatment of Diffuse Alveolar Hemorrhage, a Diagnostic Necessity before Using High-dose Glucocorticoids

A 46-year-old woman with exacerbating hemoptysis and dyspnea was diagnosed with diffuse alveolar hemorrhage (DAH). High doses of glucocorticoids were initiated, but afterward, paroxysmal hypertension (210/140 mmHg) with headache and abdominal pain appeared. A 50-mm left adrenal tumor with an intense uptake by iodine-123 metaiodobenzylguanidine scintigraphy and catecholamine hypersecretion revealed complication with pheochromocytoma. Because high doses of glucocorticoids, sometimes required for DAH, can provoke life-threatening paroxysmal hypertension in pheochromocytoma and paraganglioma (PPGL), our case suggests that PPGL needs to be recognized as the cause of DAH and should be detected with whole-body imaging before starting glucocorticoids.

Recent advances in the management of pheochromocytoma and paraganglioma

Pheochromocytomas and paragangliomas (PPGLs) are rare tumors that cause refractory hypertension and hypertensive crisis. Although metastatic disease accounts for 30% of PPGLs, the diagnosis of malignancy is difficult without the presence of metastatic lesions. Here, we review several advancements in the diagnosis and treatment of PPGL. A nationwide epidemiological survey in Japan revealed that the annual number of patients with PPGL was 3000, which was higher than that reported previously. While plasma and urine fractionated metanephrines are recommended for use in specific biochemical testing for diagnosis, creatinine-corrected fractionated metanephrines in spot urine samples that had been widely used in Japan as a convenient screening test were shown to be as useful as 24-h urine fractionated metanephrines. Regarding imaging studies, a more specific functional imaging for PPGLs, ⁶⁸Ga DOTATATE, was newly developed. ⁶⁸Ga DOTATATE provides a clear image with high sensitivity and specificity. Currently, PASS or GAPP histological scores and SDHB immunostaining are clinically used to attempt to discriminate benign from malignant tumors. However, since this distinguishing process remains difficult, all cases were classified as malignant with the possibility of metastasis in the WHO classification of endocrine tumors updated in 2017. Approximately 60% of PPGLs have germline mutations in PPGL-related genes. Currently, the genes are classified into two clusters based on their mechanism for the etiology of tumorigenesis. Based on the possible mechanisms of tumor development associated with gene mutations, several molecular target drugs are under evaluation to explore more promising treatments for malignant PPGL.

Preoperative Management of Pheochromocytoma and Paraganglioma

Pheochromocytoma and paraganglioma (PPGL) are rare neuroendocrine tumors, characterized by excessive release of catecholamines (CAs), and manifested as the classic triad of headaches, palpitations, profuse sweating, and a variety of other signs and symptoms. The diagnosis of PPGL requires both evidence of excessive release of CAs and anatomical localization of CA-secreting tumor. Surgery is the mainstay of treatment for all patients with PPGL unless contraindicated. However, without proper preparation, the release of excessive CAs, especially during surgery, can result in lethal cardiovascular complications. Herein, we briefly reviewed the pathogenesis of this disease, discussed the current approaches and evidence available for preoperative management, summarizing the results of the latest studies which compared the efficacies of preoperative management with or without α adrenergic-receptor antagonists, aiming to facilitate better understanding of the preoperative management of PPGL for the physicians.

An ectopic renin-secreting adrenal corticoadenoma in a child with malignant hypertension

A previously healthy 7‐year‐old male presented with hypertensive emergency, hypokalemia, and elevated plasma renin activity and aldosterone levels. There was no evidence of virilization or cushingoid features. MRI of the abdomen revealed a large (5 × 5 × 3 cm) peripherally enhancing, heterogeneous mass arising from the left adrenal gland. The patient was treated for a suspected pheochromocytoma. However, his blood pressure was not responsive to alpha‐blockade. Blood pressure was controlled with a calcium channel blocker and an angiotensin‐converting enzyme (ACE) inhibitor. A complete surgical resection of the mass was performed. Postoperatively, his blood pressure normalized and he did not require antihypertensives. On pathological examination, the tumor tissue stained negative for chromogranin and positive for renin. The final diagnosis was renin‐secreting adrenal corticoadenoma, an extremely rare adrenal tumor not previously reported in a pediatric patient. Malignant hypertension due to a renin‐secreting tumor may need to be distinguished from a pheochromocytoma if alpha‐adrenergic blockade is ineffective.

Are patients with hormonally functional phaeochromocytoma and paraganglioma initially receiving a proper adrenoceptor blockade? A retrospective cohort study

OBJECTIVE

Pharmacological treatment is mandatory in patients with hormonally functional phaeochromocytoma and paraganglioma (PHAEO/PGL). We evaluated if patients initially diagnosed with hormonally functional PHAEO/PGL by various medical subspecialties received proper adrenoceptor blockade, and analysed factors predicting the prescription of adequate treatment.

METHODS

In a retrospective cohort study, we reviewed data from patients initially diagnosed with hormonally functional PHAEO/PGL outside the National Institutes of Health and Cedars-Sinai Medical Center, who were referred to these institutions between January 2001 and April 2015. Logistic regression was used to assess factors associated with proper adrenoceptor blockade.

RESULTS

A total of 381 patients were included. Adequate pharmacological treatment was prescribed to 69·3%, of which 93·1% received α-adrenoceptor blockers. Regarding patients who were inappropriately treated, 53% did not receive any medication. Independent predictors of the prescription of a proper blockade were the diagnosis by endocrinologists [odds ratio (OR) 4·14; 95% confidence interval (CI), 2·51-6·85; P < 0·001], the presence of high blood pressure (OR 5·94; 95% CI, 3·11-11·33; P < 0·001) and the evidence of metastasis (OR 5·96; 95% CI, 1·93-18·46; P = 0·002).

CONCLUSIONS

Although most patients received adequate pharmacological treatment, almost one-third were either not treated or received inappropriate medications. The diagnosis by endocrinologists, the presence of high blood pressure and the evidence of metastatic disease were identified as independent predictors of a proper blockade. These results highlight the need to educate physicians about the importance of starting adequate adrenoceptor blockade in all patients with hormonally functional PHAEO/PGL.

Evaluating the optimum rest period prior to blood collection for fractionated plasma free metanephrines analysis

Introduction

The high diagnostic accuracy of plasma metanephrines (PMets) in the diagnosis of Phaeochromocytoma/Paraganglioma (PPGL) is well established. Considerable controversy exists regarding optimum sampling conditions for PMets. The use of reference intervals that do not compromise diagnostic sensitivity is recommended. However, the optimum rest period prior to sampling has yet to be clearly established. The aim of this study was to evaluate PMets concentrations in paired blood samples collected following 30 and 40 min seated-rest prior to sampling, in patients in whom it was clinically reasonable to suspect that PPGL may be present.

Design and Methods

A retrospective cross-sectional study design was used. PMets results from paired blood samples collected after 30 and 40 min seated-rest between January 2009 and June 2015 were recorded. Results were interpreted using reference intervals established in subjects seated and supine.

Results

A total of 410 patient results were eligible for analysis. There was no statistical difference between plasma normetanephrine (NMN) or metanephrine (MN) concentrations in samples collected following 30 and 40 min seated-rest in subjects with PPGL (n=11), post-resection of PPGL (n=20) or in whom PPGL was excluded (n=379). Using reference intervals established in the seated position, diagnostic sensitivity was 100% at 30 min and 90.9% at 40 min. Diagnostic specificity was approximately 95% at both time points. When supine reference intervals were used, diagnostic sensitivity was 100% and diagnostic specificity was reduced by ≈22% at both time points.

Conclusion

Based on these data, we recommend at most 30 min continuous rest prior to sampling for PMets measurement.

Paraganglioma-induced alveolar hemorrhage

A 21-year-old man twice developed sudden dyspnea during running examinations for promotion. Chest computed tomography (CT) revealed lobular ground-glass opacity and centrilobular shadows bilaterally. The bronchoscopy findings were consistent with alveolar hemorrhage, and echocardiography showed severe hypokinesia a few hours later. A mass was subsequently identified along the abdominal aorta on enhanced CT and iodine-131 metaiodobenzylguanidine scintigraphy. Catecholamine oversecretion, which was later confirmed, may have increased the pulmonary vein pressure, thus resulting in the development of an alveolar hemorrhage, and damaged the cardiac muscles as manifested by hypokinesia. Since the patient had not previously developed alveolar hemorrhage during usual exercise, emotional stress superimposed on the physical activity may have triggered the paraganglioma to secrete excessive catecholamines, thus resulting in the observed symptoms.

Pheochromocytoma and paraganglioma: an endocrine society clinical practice guideline

OBJECTIVE

The aim was to formulate clinical practice guidelines for pheochromocytoma and paraganglioma (PPGL).

PARTICIPANTS

The Task Force included a chair selected by the Endocrine Society Clinical Guidelines Subcommittee (CGS), seven experts in the field, and a methodologist. The authors received no corporate funding or remuneration.

EVIDENCE

This evidence-based guideline was developed using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system to describe both the strength of recommendations and the quality of evidence. The Task Force reviewed primary evidence and commissioned two additional systematic reviews.

CONSENSUS PROCESS

One group meeting, several conference calls, and e-mail communications enabled consensus. Committees and members of the Endocrine Society, European Society of Endocrinology, and Americal Association for Clinical Chemistry reviewed drafts of the guidelines.

CONCLUSIONS

The Task Force recommends that initial biochemical testing for PPGLs should include measurements of plasma free or urinary fractionated metanephrines. Consideration should be given to preanalytical factors leading to false-positive or false-negative results. All positive results require follow-up. Computed tomography is suggested for initial imaging, but magnetic resonance is a better option in patients with metastatic disease or when radiation exposure must be limited. (123)I-metaiodobenzylguanidine scintigraphy is a useful imaging modality for metastatic PPGLs. We recommend consideration of genetic testing in all patients, with testing by accredited laboratories. Patients with paraganglioma should be tested for SDHx mutations, and those with metastatic disease for SDHB mutations. All patients with functional PPGLs should undergo preoperative blockade to prevent perioperative complications. Preparation should include a high-sodium diet and fluid intake to prevent postoperative hypotension. We recommend minimally invasive adrenalectomy for most pheochromocytomas with open resection for most paragangliomas. Partial adrenalectomy is an option for selected patients. Lifelong follow-up is suggested to detect recurrent or metastatic disease. We suggest personalized management with evaluation and treatment by multidisciplinary teams with appropriate expertise to ensure favorable outcomes.

Neurologic complications of disorders of the adrenal glands

Disorders of the adrenal glands frequently have secondary neurological manifestations, while some diseases that involve the central nervous system are accompanied by adrenal gland dysfunction. Excessive corticosteroid secretions in primary or secondary Cushing's syndrome causes muscle weakness and behavioral disturbances, such as emotional lability and sometimes depression, while adrenal insufficiency may cause fatigue, weakness, and depression. Adrenoleukodystrophy and adrenoneuromyelopathy are X-linked recessive disorders of the metabolism of very long chain fatty acids that manifest with white matter abnormalities of the brain, myelopathy and/or neuropathy, as well as adrenal insufficiency. Other disorders of the adrenal glands include hyperaldosteroidism, which may cause weakness from hypokalemia. Dysfunction of the adrenal medulla causes excessive or deficient secretion of catecholamines, primarily causing cardiovascular symptoms. This chapter reviews the clinical manifestations and diagnostic aspects and treatment of the various disorders of the adrenal glands. Some of the congenital adrenal diseases are also discussed.

Different diagnostic cut-off values of urinary fractionated metanephrines according to sex for the diagnosis of pheochromocytoma in Korean subjects

The diagnosis of pheochromocytoma depends on the documentation of catecholamine overproduction. The use of urinary fractionated metanephrines has recently become common for the diagnosis of pheochromocytoma. In order to avoid false positive and false negative results, optimal cut-off levels are necessary; however, there have been few published reports on whether different cut-off levels are needed to diagnose pheochromocytoma according to sex. We reviewed the medical records of 815 subjects (including 103 pheochromocytoma patients) whose of 24-h urinary fractionated metanephrine was measured using high-performance liquid chromatography methods and adrenal imaging at Samsung Medical Center. Receiver operating characteristic (ROC) curves were used to determine cut-off values according to sex. The upper limit values of fractionated metanephrine in healthy volunteers and the control group were significantly higher in male subjects compared with females. When we applied cut-off values according to sex, the diagnostic efficacies (defining a positive test as either metanephrine or normetanephrine levels above the cut-off value) were a sensitivity of 96% in male subjects and 98.1% in female subjects and a specificity of 88.6% in male subjects and 94.1% in female subjects. However, when we applied cut-off values without considering sex, the specificity decreased from 88.6% to 77.8% in male subjects. In this study, urinary fractionated metanephrines had a high level of sensitivity and specificity for the diagnosis of pheochromocytoma. However, diagnostic cut-off values were higher in male subjects than in female subjects. Therefore, different cut-off values may be needed according to sex to diagnose pheochromocytoma in Koreans.

Adrenal causes of hypertension: pheochromocytoma and primary aldosteronism

The clinical presentations of the patient with pheochromocytoma -- a rare endocrine neoplasm -- include adrenal incidentaloma, hypertensive paroxysms, sustained apparent polygenic hypertension, hypertension in pregnancy, and hypertensive crisis induced by anesthesia. Although when undiagnosed a pheochromocytoma can be lethal, it can usually be cured with surgery. Biochemical documentation with measurements of fractionated metanephrines and catecholamines should precede imaging studies. Abdomen and pelvis computed imaging is usually the first imaging test. Careful preoperative pharmacologic preparation is important for a successful surgical outcome. Adrenal pheochromocytomas can usually be removed laparoscopically, whereas, catecholamine-secreting paragangliomas typically require an open approach. All first degree relatives of pheochromocytoma patients should have biochemical testing. In addition, molecular genetic testing for germline mutations should be considered in most patients with adrenal pheochromocytoma and in all patients with paraganglioma. Primary aldosteronism is a relatively common form of secondary hypertension -- affecting 5 to 10% of all patients with hypertension. A plasma aldosterone concentration (PAC) to plasma renin activity (PRA) ratio should be obtained in patients with hypertension and hypokalemia, resistant hypertension, adrenal incidentaloma and hypertension, onset of hypertension at a young age (e.g., < 20 years of age), severe hypertension (e.g., > or =160 mm Hg systolic or > or =100 mm Hg diastolic), or whenever the clinician is considering other forms of secondary hypertension. The PAC/PRA ratio is a case finding test and a positive result should be confirmed with aldosterone suppression testing with either oral or intravenous sodium loading. The treatment goals for patients with primary aldosteronism are to prevent the morbidity and mortality associated with hypertension, hypokalemia, and cardiovascular damage. Both the subtype of primary aldosteronism and patient preference should dictate the treatment approach.

The diagnostic efficacy of urinary fractionated metanephrines measured by tandem mass spectrometry in detection of pheochromocytoma

BACKGROUND

There are limitations to currently available biochemical tests for pheochromocytoma. Our objective was to evaluate the diagnostic efficacy of a novel tandem mass spectrometry assay for the measurement of fractionated urinary metanephrines in patients suspected to have a pheochromocytoma. We also developed clinically based cut-offs for positivity of this measurement.

METHODS

We examined the medical records of 506 patients (including 102 patients with a catecholamine-producing tumour) who underwent measurement of 24-h urinary fractionated metanephrines using tandem mass spectrometry as well as adrenal imaging at Mayo Clinic, Rochester. The cut-offs for positivity were defined as follows: total metanephrines (sum of the metanephrine fractions) 5163 nmol/day, normetanephrine fraction 4001 nmol/day, metanephrine fraction 1531 nmol/day. Receiver operating characteristic (ROC) curves were constructed.

RESULTS

The diagnostic efficacy was as follows: normetanephrine fraction sensitivity 87.3% [(95% confidence interval (CI) 79.4-92.4%], specificity 95.0% (92.5-96.8); metanephrine fraction sensitivity 56.9% (47.2-66.1), specificity 95.0% (92.5-96.8); elevation of either normetanephrine or metanephrine fraction sensitivity 97.1% (91.7-99.0) and specificity 91.1% (87.9-93.5). Areas under the ROC curves (AUCs) were 0.972 (95% CI 0.955-0.990) for the normetanephrine fraction, 0.800 (0.741-0.858) for the metanephrine fraction, 0.991 (0.985-0.996) for total metanephrines, and 0.991 (0.985-0.996) for a regression-derived ROC curve incorporating both the metanephrine and normetanephrine fractions.

CONCLUSION

Measurement of 24-h urinary fractionated metanephrines by a tandem mass spectrometry assay appears to be an effective biochemical technique in the investigation of pheochromocytoma.

Pheochromocytoma: challenges in diagnosis and nursing care

Pheochromocytomas are catecholamine-secreting tumors arising from chromaffin cells of the sympathoadrenal system, which includes the adrenal medulla and sympathetic ganglionic tissue. The effects of catecholamine excess cause potentially fatal symptomologies and end-organ damage if not diagnosed and treated. If diagnosed and removed surgically, most of these patients can be cures. Pheochromocytomas are rare and affect from two to eight per million people. There are 800 deaths in the United States annually as a result of complications. Of patients who have pheochromocytomas diagnosed at autopsy, 75% died suddenly from myocardial infarction or cerebral vascular catastrophe. Challenges in diagnosis, tumor location, and treatment are considerable.

Recommedition for Apllication and Determination Tumor Markers of Neuroendocrine System

Neuroendokrini tumori vode poreklo iz neuroendokrinih ćelija, koji pod uslovima specifične stimulacije sekretuju hormone, regulišući niz različitih funkcija u organizmu. U radu je opisana grupa neuroendokrinih tumora koja se sastoji od: karcinoida endokrinih tumora pankreasa, neuroblastoma, medularnog karcinoma tiroidee i feohromocitoma. Biće diskutovani tumori koji potiču iz endokrinih žlezda, kao i oni koji vode poreklo iz takozvanog »difuznog« neuroendokrinog ćelijskog sistema gastrointestinalnog trakta. Radi se o najvećem endokrinom organu u organizmu. Oko 50 različitih neuroendokrinih ćelijskih tipova gastrointestinalnog trakta je indentifikovano. Važan dijagnostički segment u tretmanu ovih tumora, je određivanje biogenih amina i peptida, čija je aktivnost izmenjena kod pojave neoplazmi. Širok je spektar kliničkih simptoma kod pojave ove vrste tumora, a svi su posledica sposobnosti tumora da sekretuju povećane količine peptinih hormona i biogenih amina. Glavni ciljevi ovog teksta su procena važnosti ove grupe tumorskih markera, kao i predlozi za njihovo koriŠćenje u našim uslovima.

[Slight hormonal alterations in a patient with a large pheochromocytoma]

We present a case report that the patient had symptoms suggesting pheochromocytoma, a large tumor (> 50 g) and a single minimally altered laboratorial test, exemplifying a diagnostic pitfall. A 31 y.o. male patient had two acute abdominal events, the last one accompanied by headache, arterial hypertension, facial flushing, perspiration and cutaneous pallor. In another admission, the patient had sustained arterial hypertension and cardiac arrhythmia. From laboratory analysis, the vanililmandelic acid was slightly modified. Scintigraphy disclosed a large adrenal mass suggesting pheochromocytoma. Histopathology confirmed this hypothesis. This report points out that patients with symptoms suggesting pheochromocytoma, even when plasma catecholamines and urinary metanephrines levels are normal, may harbor large tumors with a high catecholamines turnover or that had undergone hemorrhagic necrosis.

Measurement of fractionated plasma metanephrines for exclusion of pheochromocytoma: Can specificity be improved by adjustment for age?

BACKGROUND: Biochemical testing for pheochromocytoma by measurement of fractionated plasma metanephrines is limited by false positive rates of up to 18% in people without known genetic predisposition to the disease. The plasma normetanephrine fraction is responsible for most false positives and plasma normetanephrine increases with age. The objective of this study was to determine if we could improve the specificity of fractionated plasma measurements, by statistically adjusting for age. METHODS: An age-adjusted metanephrine score was derived using logistic regression from 343 subjects (including 33 people with pheochromocytoma) who underwent fractionated plasma metanephrine measurements as part of investigations for suspected pheochromocytoma at Mayo Clinic Rochester (derivation set). The performance of the age-adjusted score was validated in a dataset of 158 subjects (including patients 23 with pheochromocytoma) that underwent measurements of fractionated plasma metanephrines at Mayo Clinic the following year (validation dataset). None of the participants in the validation dataset had known genetic predisposition to pheochromocytoma. RESULTS: The sensitivity of the age-adjusted metanephrine score was the same as that of traditional interpretation of fractionated plasma metanephrine measurements, yielding a sensitivity of 100% (23/23, 95% confidence interval [CI] 85.7%, 100%). However, the false positive rate with traditional interpretation of fractionated plasma metanephrine measurements was 16.3% (22/135, 95% CI, 11.0%, 23.4%) and that of the age-adjusted score was significantly lower at 3.0% (4/135, 95% CI, 1.2%, 7.4%) (p < 0.001 using McNemar's test). CONCLUSION: An adjustment for age in the interpretation of results of fractionated plasma metanephrines may significantly decrease false positives when using this test to exclude sporadic pheochromocytoma. Such improvements in false positive rate may result in savings of expenditures related to confirmatory imaging.

Intrahepatic cholestasis as a paraneoplastic syndrome associated with pheochromocytoma

Pheochromocytoma is a rare tumor of chromaffin cells that secrete catecholamines and several cytokines. The clinical manifestations are protean and may include hypertension, weight loss, sweating, palpitation, headache, anxiety, tremor, nausea, vomiting, and hypercalcemia. The tumor can mimic many unrelated diseases, leading to significant delay and difficulty in diagnosis. We report a case of a 37-yr-old male admitted with jaundice, dark urine, fever, and signs of a systemic inflammatory response. Abdominal computed tomography revealed a heterogeneously enhancing tumor between the pancreatic tail and left kidney. There was no evidence of obstruction to bile flow, neoplastic involvement of the liver or bile ducts, or infectious etiology. The tumor was removed and found to be a pheochromocytoma. Immunohistochemical analysis revealed the presence of interleukin-1beta in the tumor cells. After surgery, the jaundice resolved without further treatment, leading us to the conclusion that it was a paraneoplastic phenomenon possibly related to interleukin-1beta production. We suggest that occult pheochromocytoma should be added to the differential diagnosis of unexplained intrahepatic cholestasis.

A systematic review of the literature examining the diagnostic efficacy of measurement of fractionated plasma free metanephrines in the biochemical diagnosis of pheochromocytoma

BACKGROUND: Fractionated plasma metanephrine measurements are commonly used in biochemical testing in search of pheochromocytoma. METHODS: 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. RESULTS: 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). CONCLUSION: 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.

Development of Enantioselective Immunoassays for Free Plasma Metanephrines

The development of an enantioselective radioimmunoassay (RIA) and enzyme immunoassay (EIA) for L-normetanephrine (NM) and L-metanephrine (M) were studied. Prior to the immunoassay, the protein matrix of the ethylenediaminetetraacetic acid (EDTA) plasma samples was removed by acid precipitation, followed by derivatization of the L-metanephrines to N-acyl-L-metanephrines. For the EIA, N-acyl-L-NM and N-acyl-L-M were bound to the surface of microtiter plates. Acylated L-metanephrines from the sample and solid-phase-bound N-acyl-L-NM or N-acyl-L-M competed for a fixed number of rabbit anti-N-acyl-NM or anti-N-acyl-M antibody binding sites. When the system was in equilibrium, free antigens and free antigen-antibody complexes were removed by washing. The antibodies bound to the respective solid-phase N-acyl-L-NM or N-acyl-L-M were detected by a goat anti-rabbit IgG-peroxidase conjugate using tetramethyl benzidine (TMB) as a substrate. The RIAs were conventional double antibody tests using the above rabbit antisera and specific (125)I-N-acyl-L-metanephrine tracers. Chiral recognition of the L-enantiomers was observed not only for the native molecules but for all N-acyl derivatives tested. The cross-reactivity to the corresponding D-enantiomers was always <1%. The detection limits were found to be approximately 0.04 nmol/L (7.5 pg/mL) for M and 0.08 nmol/L (15 pg/mL) for NM in RIA and EIA.

Maximizing Efficacy of Endocrine Tests: Importance of Decision-focused Testing Strategies and Appropriate Patient Preparation

The efficacy of endocrine tests depends on the choice of tests, the preparation of the patients, the integrity of the specimens, the quality of the measurements, and the validity of the reference data. Close dialogue among the clinicians, the laboratory, and the patients is a key factor for optimal patient care. The characteristics of urine and plasma samples and the advantages and limitations of paired test measurements are presented. The importance of test sequence strategies, provocative or inhibitory procedures, and elimination of drug interferences is illustrated with four cases involving Cushing syndrome, pheochromocytoma, primary aldosteronism, and hypercalcemia. For each of these scenarios, key clinical issues are highlighted, along with discussions of the best test strategies, including which medications are likely to interfere. The importance of targeting laboratory tests to answer well-focused clinical decisions is emphasized. The roles of some time-honored provocative procedures are questioned in light of more sensitive and specific analytic methods. The importance of decision-focused analytical tolerance limits is emphasized by demonstrating the impact of analytic bias on downstream medical resource utilization. User-friendly support systems to facilitate the implementation of test strategies and postanalytic tracking of patient outcomes are presented as essential requirements for quality medical practice.

Pheochromocytoma and primary aldosteronism: diagnostic approaches

Although adrenal-dependent hypertension is an uncommon form of hypertension, its diagnosis provides clinicians with a unique treatment opportunity, that is, to render a surgical cure or to achieve a dramatic response to pharmacologic therapy. The diagnosis of catecholamine-secreting tumors has evolved during the last 70 years to a straightforward stepwise algorithmic approach. Primary aldosteronism is now recognized as the most common form of secondary hypertension, and the screening methods for it are simple and reliable.

Spells: in search of a cause

OBJECTIVE

To determine the cause of spells, present clinical features, and discuss diagnostic approaches.

DESIGN

Relevant medical literature is reviewed, and three illustrative cases are presented.

RESULTS

Spells are a sudden onset of a symptom or symptoms that are stereotypic, self-limited, and recurrent. A spell involves both subjective perceptions and objective findings. In the assessment of patients who have spells, use of a systematic approach is important in determining the cause. The causes of spells include endocrine, cardiovascular, psychologic, pharmacologic, neurologic, and other miscellaneous disorders. A comprehensive history, physical examination, and basic laboratory studies are important in the initial assessment. Specialized testing is usually needed and directed by clinical suspicion based on the spell "phenotype" (for example, a pheochromocytoma, carcinoid syndrome, or mast cell disease) and the type of facial flush or pallor.

CONCLUSION

In the assessment of the patient who has spells, the clinician should cast a wide but defensible diagnostic net. Initial studies should be directed by the clues obtained from the history and physical examination.