Plasma adrenomedullin concentrations in patients with adrenal pheochromocytoma

Background: The hypotensive peptide adrenomedullin was first isolated in ex tracts of human pheochromocytoma. There is, however, no information availab le on the behaviour of circulating adrenomedullin or on the correlation wit h catecholamines in patients with pheochromocytoma. Objectives: I)to invest igate whether plasma adrenomedullin levels were changed in 10 patients with pheochromocytoma when compared to 21 healthy subjects and 16 patients with essential hypertension; 2) to determine whether or not adrenomedullin has a counterregulatory role in catecholamine excess in pheochromocytoma or is responsible for hemodynamic modifications before and after tumour resection ; 3) to determine tissue distribution of iradrenomedullin in the pheochromo cytoma. Methods: Plasma adrenomedullin and catecholamine levels were measur ed in all patients with pheochromocytoma before and four weeks after tumour removal. In the four patients undergoing resection of tumours, plasma leve ls of adrenomedullin were measured at different time-points during surgery. Results: The mean plasma adrenomedullin concentrations (+/- SD) in patient s with pheochromocytoma (37.9 +/- 6 pg/ml) were significantly higher (p < 0 .0001) than those in normal subjects (13.7 +/- 6.1 pg/ml) and patients with essential hypertension (22.5 +/- 9.1 pg/ml). Adrenomedullin levels correla ted with plasma noradrenaline (r = 0.516, p = 0.0124). In all patients with pheochromocytoma, plasma adrenomedullin concentrations decreased after rem oval of tumours (from 37.9 +/- 6 to 10.9 +/- 4.6 pg/ml; p ( 0.0001). In the four patients studied during surgery, baseline plasma adrenomedullin and n oradrenaline levels were markedly elevated, and increased significantly wit h tumour manipulation, decreasing 24 hours after operation. Adrenal medulla cells surrounding the pheochromocytoma site stained for ir-adrenomedullin, whereas only isolated cells of pheochromocytoma stained for the peptide. C onclusions: This study demonstrates that circulating adrenomedullin is incr eased in pheochromocytoma, and is also correlated with plasma noradrenaline levels. Adrenomedullin may represent an additional biochemical parameter f or clinical monitoring of patients with pheochromocytoma.