Ketoconazole, used in clinical practice as an antifungal medication, recently was found to be a potent inhibitor of gonadal and adrenal steroidogenesis in vitro and in vivo. The effects of prolonged treatment with this agent in Cushing's disease were investigated in five patients who had recurrent severe hypercortisolism after selective transsphenoidal surgery. The patients received the drug for at least 2 months. Urinary cortisol markedly decreased in all patients immediately after the beginning of treatment with ketoconazole (800 mg/day) and remained within low normal levels when the daily dose was lowered to 600 mg/day. Plasma cortisol also decreased. After 4-6 weeks of treatment, the clinical features of the disease regressed in all patients without signs of toxicity. These findings indicate that ketoconazole may be a valuable drug for the management of patients with Cushing's disease because of its ability to correct hypercortisolism quickly.

As muscle wasting and resistance to insulin-mediated glucose utilization are features of Cushing's syndrome (CS), we examined glucose and amino acid metabolism in six patients with CS and six normal subjects before and during euglycemic hyperinsulinemic clamp studies (plasma insulin concentrations, approximately 0.36, approximately 0.65, and approximately 10.05 mmol/L). The two groups had similar body mass index values. In the postabsorptive state, leucine and alpha-ketoisocaproate (KIC) rates of appearance (Ra), KIC oxidation, and nonoxidized leucine-carbon flux, an index of leucine entering protein (Leu----P), were comparable in CS patients [2.38 +/- 0.14 (+/- SE), 0.22 +/- 0.04, and 2.16 +/- 0.12 mumol/kg.min) and in normal subjects (2.73 +/- 0.25, 0.17 +/- 0.02, and 2.59 +/- 0.22 mumol/kg.min). During the euglycemic clamp studies the leucine and KIC Ra values, KIC oxidation, and Leu----P decreased to a similar extent in both groups. In contrast, insulin-mediated glucose utilization was impaired in the CS patients at each clamp step (P less than 0.05). In summary, postabsorptive whole body leucine metabolism is normal in patients with CS and is normally suppressed by hyperinsulinemia, indicating a dissociation in insulin sensitivity with respect to glucose and amino acid metabolism.

The effect of exogenous ovine Corticotropin-Releasing Hormone (oCRH) on plasma ACTH and cortisol levels was investigated in 10 normal volunteers and in 37 patients with Cushing's syndrome (26 with pituitary-dependent disease, 5 with an adrenal adenoma, 2 with an adrenal carcinoma and 4 with bilateral nodular hyperplasia). In all normal subjects and in patients with Cushing's disease, oCRH 100 micrograms as a bolus produced an increase in both plasma ACTH and cortisol. The peak of ACTH occurred after 15-30 min, while plasma cortisol showed highest levels between 30 and 60 min after oCRH administration. The hormonal response in Cushing's disease showed great variability with a clear hyperresponsiveness at least in 6 out of 26 patients with Cushing's disease. A slight and delayed response occurred in 3 cases of bilateral nodular adrenal hyperplasia, while a fourth case showed hyperresponsiveness similar to that found in pituitary-dependent Cushing's disease. No response was observed in patients with an adrenal tumor. Eleven patients with Cushing's disease were tested before and 1 month after pituitary microadenomectomy. After surgery basal cortisol levels were reduced in 10 and became unresponsive or less responsive to oCRH. ACTH patterns were variable with a normal response only in few cases. Although this test seems of limited value in the diagnosis of hypercortisolism, it is a useful tool to differentiate some types of Cushing's syndrome (adrenal tumor from pituitary-dependent Cushing's disease). Variable patterns of response in cases with bilateral nodular adrenal hyperplasia limit the usefulness of this test in recognizing this rare form of hypercortisolism.

To define the role of dopaminergic drugs on pituitary ACTH secretion, we studied the effect of a dopamine-agonist, lisuride, on a group of 9 patients with pituitary dependent Cushing's syndrome. Lisuride (0.4-0.6 mg/day) was administered for two days: in only two out of eight cases the ACTH levels, sampled every 30 min for 6 h (08:00-14:00 h), showed some reduction when compared with the control day. Two of the nonresponders (R.P.; B.F.) and one untested patient (L.E.) were then treated chronically with a similar amount of lisuride per day for 20 days (L.E.) and for 4 months (B.F.; R.P.). One patient (L.E.) showed a clear decrease in urinary free cortisol without clinical improvement; while in the other two cases, followed for a longer period of time, a clinical improvement was observed together with a decrease of the hormonal parameters. In conclusion, lisuride may occasionally reduce ACTH secretion in patients with pituitary dependent Cushing's syndrome, but the acute test fails to identify the patients who would benefit from this treatment.

Three patients presented with hyperpigmentation and high plasma levels of ACTH 4-5 years after bilateral adrenalectomy for Cushing's "disease". X-rays and ct-scan of the lungs showed a small pulmonary mass in all. ACTH levels (1100-2000 pg/ml) were not suppressible by high doses hydrocortisone. A carcinoid tumor was removed in two cases and a chemodectoma in the third. Evidence for ACTH secretion by these tumors was provided by both decrease of ACTH levels after surgery and/or in vitro studies. Both carcinoid cultures showed a basal ACTH production, which was clearly increased by LVP (10(-7) M) and CRF (10(-7) M). Our findings in vitro studies suggest the presence of specific receptor sites for physiological stimuli (LVP and CRF) in tumor cell membranes.