title: Multicenter study on the diagnostic value of a new RIA for the detection of free plasma metanephrines in the work-up for pheochromocytoma.
abstract: Available laboratory test methods for the detection of elevated concentrations of catecholamines and their metabolites in urine and/or plasma are not always sensitive enough for the detection of pheochromocytoma. High-quality immunoassays for these compounds appear to be as accurate as high-pressure liquid chromatography (HPLC) or gas chromatography/mass spectrometry (GC-MS). Therefore, the current project aims to establish a new sensitive radioimmunoassay (RIA) for the measurement of free metanephrines in the plasma of patients in the work-up for pheochromocytoma. We report first results of an ongoing multicenter clinico-chemical evaluation study in hypertensive patients and normotensive volunteers. After an overnight fast plasma samples were collected on ice in EDTA- and heparin-coated tubes after insertion of an indwelling venous line and resting in the supine (patients) or sitting position (normal volunteers) for 30 min. Plasma metanephrines were measured by a newly developed RIA from IBL, Hamburg, Germany. Good agreement of the assay with the tandem mass spectrometry (LC-MS/MS) method for normetanephrine (r2=0.975) and for metanephrine (r2=0.985) could be demonstrated. Both specimens, EDTA and heparin plasma, can be used with the same results. The RIA has a good precision of <15% in the normal range and of <10% in the elevated concentration range. Our preliminary data suggest a high validity of the newly developed RIA for measuring free metanephrine and normetanephrine in hypertensive subjects in both EDTA and heparin plasma. Further work is required to determine the accuracy of the test in larger patient populations and in patients with pheochromocytoma.
authors.affiliation: Kuratorium für Dialyse und Nierentransplantation e.V. Kidney Center, Ludwigshafen, Germany. Tomas.Lenz@kfh-dialyse.de
authors.forename: Tomas
authors.initials: T
authors.lastname: Lenz
authors.forename: Joachim
authors.initials: J
authors.lastname: Zorner
authors.forename: Carl
authors.initials: C
authors.lastname: Kirchmaier
authors.forename: Daniele
authors.initials: D
authors.lastname: Pillitteri
authors.forename: Klaus
authors.initials: K
authors.lastname: Badenhoop
authors.forename: Christine
authors.initials: C
authors.lastname: Bartel
authors.forename: Helmut
authors.initials: H
authors.lastname: Geiger
authors.forename: Katrin
authors.initials: K
authors.lastname: Hasselbacher
authors.forename: Ulrich
authors.initials: U
authors.lastname: Tuschy
authors.forename: Jürgen
authors.initials: J
authors.lastname: Westermann
authors.forename: Lothar
authors.initials: L
authors.lastname: Salewski
mesh_terms: D000310:Adrenal Gland Neoplasms / Q000097:blood / Q000175:diagnosis*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008676:Metanephrine / Q000097:blood*; D008875:Middle Aged; D010673:Pheochromocytoma / Q000097:blood / Q000175:diagnosis*; D011863:Radioimmunoassay / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D008676:Metanephrine