Pro-gamma-MSH levels in various disorders of pituitary-adrenal axis.

N-Terminal (1-76) portion of proopiomelanocortin (hNT) was measured in normals, Addison's, Nelson's, Cushing's disease, and in dexamethasone suppressible hyperaldosteronism (DSH) by using a specific homologous RIA. Mean basal immunoreactive hNT level was 94.2 +/- 6 pg/ml (mean +/- SE) in normal subjects. In Cushing's disease hNT values were slightly but not significantly (121 +/- 26.5 pg/ml) higher. In patients with DSH the levels were within normal range while they were much higher in Addison's and Nelson's syndromes. A strong correlation was found between IR-hNT and ACTH in plasma of normal subjects and patients with different disorders of the pituitary-adrenal axis (r = 0.83, p less than 0.01). Corticotropin-Releasing-Hormone (CRH) test in Cushing's disease stimulated the release of both ACTH and IR-hNT, showing a slightly different pattern of secretion. Similar patterns of secretion were found for hNT and ACTH in various pituitary-adrenal abnormalities. Normal levels of hNT in DSH do not support a role of this peptide in the pathogenesis of the disorder. Measurement of hNT in plasma can provide an additional tool for the diagnosis of patients with various disorders of the hypothalamic-pituitary-adrenal axis.