EVALUATION OF URINARY METANEPHRINE AND NORMETANEPHRINE ENZYME-IMMUNOASSAY (ELISA) KITS BY COMPARISON WITH ISOTOPE-DILUTION MASS-SPECTROMETRY

Determination of urinary 3-O-methylated catecholamines (metanephrines) is generally considered a principal test for the clinical chemical di agnosis of pheochromocytoma and is currently performed predominantly w ith chromatographic techniques such as gas-liquid chromatography and H PLC. Enzyme immunoassays based on microtiter plate technology have rec ently been developed for the quantitative determination of urinary met anephrine (M) and normetanephrine (NM). We compared the results for ur inary M and NM determined by these ELISA methods with those obtained b y a recently developed isotope dilution mass spectrometric method. Fro m this comparative study we can conclude that the investigated ELISA m ethods are applicable in the quantification of urinary M and thus can be successfully used to establish the diagnosis of pheochromocytoma. T hese relatively simple methods can be executed in any clinical laborat ory and in time may replace the present, more complicated, chromatogra phic techniques.