Horm Metab Res 2009; 41(9): 676-679
DOI: 10.1055/s-0029-1224133
Humans, Clinical

© Georg Thieme Verlag KG Stuttgart · New York

The Value of Immunoassays for Metanephrines in the Biochemical Diagnosis of Pheochromocytomas

N. Unger 1 , T. Deutschbein 1 , M. K. Walz 2 , K. Mann 1 , S. Petersenn 1
  • 1Department of Endocrinology and Division of Laboratory Research, Medical Center, University of Duisburg-Essen, Essen, Germany
  • 2Department of Surgery and Center of Minimally Invasive Surgery, Kliniken Essen-Mitte, Essen, Germany
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Publikationsverlauf

received 18.12.2008

accepted 24.04.2009

Publikationsdatum:
25. Juni 2009 (online)

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Abstract

An undiagnosed pheochromocytoma may result in life-threatening consequences. The diagnosis of pheochromocytoma is based on the overproduction of catecholamines. Highly sensitive biochemical assays are essential to avoid false-negative results. Determinations of 24-h urinary epinephrine and norepinephrine levels are established diagnostic tools. However, they may be falsely negative in patients with a biochemically-silent or periodically-secreting pheochromocytoma. Metanephrines, which are metabolites of catecholamines, have been suggested as an alternative diagnostic tool. Urinary metanephrines are determined by high-pressure liquid chromatography (HPLC) in an increasing number of laboratories, whereas plasma metanephrines measured by HPLC are available in specialised centres only. The different HPLC methods may be cost- and time-intensive. Immunoassays such as radio- or enzyme-immunoassays may be alternative procedures. Measurement of metanephrines instead of catecholamines by either technique improved the diagnostic accuracy for the diagnosis of pheochromocytomas. Determination of plasma free metanephrines demonstrated a higher accuracy than their urinary counterparts. The use of immunoassays may be an alternative to the laborious HPLC, although the method needs to be evaluated in more detail.