Incidental adrenal nodules: Association with exaggerated 17-hydroxyprogesterone response to adrenocorticotropic hormone

The etiology of incidentally discovered, nonfunctional adrenal nodules was evaluated by using the 17-hydroxyprogesterone (17-OHP) response to synthetic adrenocorticotrophin (cosyntropin) (ACTH) administration. Patients who were discovered to have adrenal nodules and age-matched volunteers were studied. A total of 12 patients with adrenal nodules and 10 control subjects were studied. None of the patients with adrenal nodules had any evidence of hormonal hypersecretion consistent with pheochromocytoma, Cushing’s syndrome or hy-peraldosteronism. All subjects had serum 17-OHP and Cortisol responses measured at baseline and at 30 and 60 min following the intravenous administration of 250 μg of ACTH. Baseline 17-OHP levels in patients with adrenal nodules were not significantly different from those of the normal controls (adrenal nodules 17-OHP: 75±13 vs control 68±11 ng/dl). After stimulation with ACTH, both 30 min and 60 min 17-OHP levels in patients with adrenal nodules (322±47 and 361 ±54 ng/dl, respectively) were significantly elevated over the responses seen with the controls (169±29 ng/dl at 30 min, p<0.015, and 158±20 ng/dl at 60 min, p<0.004). Baseline and post-ACTH serum Cortisol levels were similar in both groups. Out of these twelve patients with adrenal nodules, nine were reevaluated twelve months later. In this group the basal 17-OHP remained comparable to normal levels (72±8.4 ng/dl) whereas the post-ACTH levels still remained exaggerated (30 and 60 min values 327±37 and 373±39 ng/dl). Our preliminary results show that an exaggerated 17-OHP response to ACTH may be a useful test to establish the benign nature of adrenal nodules. It is postulated that in some of these patients the adrenal tissue may have genetically determined or acquired 21-hydroxylase deficiency.