A Comparison of Biochemical Tests for Pheochromocytoma: Measurement of Fractionated Plasma Metanephrines Compared with the Combination of 24-Hour Urinary Metanephrines and Catecholamines

Abstract

We compared the diagnostic efficacy of fractionated plasma metanephrine measurements to measurements of 24-h urinary total metanephrines and catecholamines in outpatients tested for pheochromocytoma at Mayo Clinic Rochester from January 1, 1999, until November 27, 2000. Catecholaminesecreting tumors were histologically proven. The sensitivity of fractionated plasma metanephrines was 97% (30 of 31 patients), compared with a sensitivity of 90% (28 of 31) for urinary total metanephrines and catecholamines (P = 0.63). The specificity of fractionated plasma metanephrines was 85% (221 of 261), compared with 98% (257 of 261; P < 0.001) for urinary measurements. The likelihood ratios for positive tests were 6.3 (95% confidence interval, 4.7 to 8.5) for fractionated plasma metanephrines and 58.9 (95% confidence interval, 22.1 to 156.9) for urinary total metanephrines and catecholamines. An adrenal pheochromocytoma was missed by urinary testing in two patients with familial syndromes and one asymptomatic patient with an incidentally discovered adrenal mass. An extra-adrenal paraganglioma was missed by plasma testing in one patient. In conclusion, measurements of 24-h urinary total metanephrines and catecholamines yield fewer false-positive results, an attribute preferred for testing low-risk patients, but fractionated plasma metanephrine measurements may be preferred in high-risk patients with familial endocrine syndromes.

A Case of Sleep Apnea Syndrome Manifesting Severe Hypertension with High Plasma Norepinephrine Levels

“…The diagnosis is made by the measurement of urinary catecholamines and the identification of tumor by CT scanning, magnetic resonance imaging, or radionucleotide scanning with MIBG or octreotide [18]. Since 90% of the cases are derived from the adrenal medulla, the measurement of the levels of urinary metanephrine, a metabolite of E, is thought to be a sensitive biochemical screening test [19][20][21][22]. In the present case, we found an elevation of urinary normetanephrine, but not metanephrine levels and failed to locate the suspected adrenal tumor on either side.…”

Evaluation of the clonidine suppression test in the diagnosis of phaeochromocytoma

“…These are constantly produced by the actions of catechol-O-methyltransferase on catecholamines leaking from stores within tumour cells and, therefore, show more consistent increases above normal in patients with phaeochromocytoma than plasma catecholamines, making this the more reliable test in these circumstances. [17][18][19][20] There is, however, still the possibility of false-positive results in which levels of metabolites are above the upper limit of normal, but not high enough to definitely diagnose phaeochromocytoma. Eisenhofer et al 6 have shown that, in such cases, clonidine suppression testing combined with measurement of plasma metanephrines can distinguish true-from false-positive results.…”

Hypertensive crisis after endoscopic ultrasound-guided fine-needle aspiration of the right adrenal gland

“…Our case shows that EUS-guided puncture of pheochromocytoma may evoke an abrupt release of catecholamines, and subsequently, a lifethreatening hypertensive crisis, similar to the well-known risk of percutaneous biopsy [2]. Based on this case, we advise exclusion of (subclinical) pheochromocytoma before all EUS-guided punctures of adrenal lesions, by 24-h urine collection for metanephrines and catecholamines [7]. A heterogeneous mass of almost 5 cm with a hypoechogenic center was seen in the right adrenal gland.…”