Cortisol and adrenocorticotropin response to desmopressin in women with Cushing's disease compared with depressive illness

The pituitary-adrenal responsiveness to desmopressin of women with depressive illness was compared with that of patients with Cushing's disease, who are known to be highly responsive, and to that of normal controls, who are known to be poorly responsive to the peptide. Although 100% of the patients in the group with Cushing's disease met the response criterion with cortisol increases of 632 +/- 80 nmol/L above baseline (mean +/- SE), the prevalence of responders was 36% in the depressive group and 10% in normal controls, with cortisol changes from baseline of 154 +/- 28 and 79 +/- 15 nmol/L, respectively. All response parameters were significantly higher in the patients with Cushing's disease and did not differ between depressive patients and normal controls, who exhibited the same general pattern of cortisol and ACTH responses. It is concluded that the desmopressin test can be used in the differentiation between depression and Cushing's disease, and that the hypothalamic-pituitary-adrenal regulation is distinct in these two conditions.