[Diagnosis of pheochromocytoma and paraganglioma: the clonidine suppression test in patients with borderline elevations of plasma free normetanephrine].

Abstract

BACKGROUND:

Measurements of plasma free metanephrines provide a sensitive test for the diagnosis of pheochromocytoma/paraganglioma (P/PGL), with highly elevated levels diagnostic of the disease. However, there is less diagnostic certainty in patients with mild elevations of these catecholamine metabolites.

PATIENTS AND METHODS:

Here we report use of the clonidine suppression test (CST) as a second-tier diagnostic test in 24 patients with mild elevations of plasma free metanephrines and/or catecholamines. Blood samples before and 3 hours after clonidine were analyzed for plasma concentrations of metanephrines and catecholamines with a negative test result defined as either a clonidine-induced fall in normetanephrine or noradrenaline by more than 40 % and 50 % respectively or to below the upper cut-offs of reference intervals.

RESULTS:

P/PGLs were confirmed in 9 patients and excluded in 15 by independent criteria. More than half of the patients without P/PGL showed normalized plasma concentrations of normetanephrine at baseline before clonidine compared to initial screening; all showed appropriate clonidine-induced falls in normetanephrine and noradrenaline or levels after the drug below upper cut-offs, indicating a diagnostic specificity of 100 % (CI 78-100 %). However, similar responses for noradrenaline were noted in 7 patients with P/PGL, indicating a diagnostic sensitivity of only 22 % (CI 2,8-60 %) compared to 100 % (CI 66-100 %) for normetanephrine.

CONCLUSION:

These results support use of the CST in combination with measurements of normetanephrine for confirming or excluding P/PGL in patients with borderline elevated test results, which should, however, first be confirmed by sampling blood under standardized resting conditions.

• Authors: R Därr, J W Lenders, K Stange, B Kindel, L C Hofbauer, S R Bornstein, G Eisenhofer
• Journal: Deutsche medizinische Wochenschrift (1946) (Dtsch Med Wochenschr) Vol. 138 Issue 3 Pg. 76-81 (Jan 2013) ISSN: 1439-4413 [Electronic] Germany
• Vernacular Title: Die Diagnose des Phäochromozytoms und Paraganglioms.
• PMID: 23299341 (Publication Type: English Abstract, Journal Article)
• Copyright: © Georg Thieme Verlag KG Stuttgart · New York.

Chemical References

• Biomarkers
• Normetanephrine
• Clonidine

Topics

• Adrenal Gland Neoplasms (blood, diagnosis)
• Adult
• Aged
• Biomarkers (blood)
• Clonidine
• Female
• Humans
• Male
• Middle Aged
• Normetanephrine (blood)
• Pheochromocytoma (blood, diagnosis)
• Reproducibility of Results
• Sensitivity and Specificity