SENSITIVITY AND SPECIFICITY OF A NEW ELISA METHOD FOR DETERMINATION OF CHROMOGRANIN-A IN THE DIAGNOSIS OF PHEOCHROMOCYTOMA AND NEUROBLASTOMA

We have evaluated a new commercially available ELISA kit for determina tion of plasma chromogranin A with respect to its usefulness in the di agnosis of neuroendocrine tumors, mainly pheochromocytoma. Serum and d ifferently anticoagulated plasmas gave different chromogranin A concen trations. Control values (n = 21) were 18.9 +/- 5.8 units/l. Chromogra nin A values > 30.4 units/l (mean + 2 S.D.) were considered elevated. In 22 patients suspected of(but found not to have) pheochromocytoma an d in 24 patients with renovascular hypertension, 18% were found to hav e elevated chromogranin A concentrations. In renovascular hypertension chromogranin A correlated positively with serum creatinine; chromogra nin A was strongly elevated especially in chronic renal failure. In 45 patients with pheochromocytoma, 13 (29%) had chromogranin A concentra tions within the normal range, as had 3 out of 11 patients with neurob lastoma (27%). In 13 pheochromocytoma patients with elevated chromogra nin A, measurements were repeated after surgical removal of the tumor; values then all fell within the normal range. We conclude that measur ement of chromogranin A adds little to already existing methods for th e diagnosis of pheochromocytoma.