Circulating cortisol & related steroids following ketoconazole challenge in Cushing's disease.

Circulating levels of cortisol, 17 alpha hydroxy progesterone and delta 4 androstenedione were analysed by specific radioimmunoassays in 11 patients with Cushing's disease before and at 2, 4, 6, 12 and 24# h following an oral dose of 400 mg ketoconazole. A significant fall in cortisol (26 - 79.6%, 59.8 +/- 18.7 SEM), delta 4 androstenedione (21.5 - 63.3%, 47.8 +/- 4.87) with a concomitant rise in 17 alpha hydroxy progesterone (113 - 218%, 116 +/- 11.43) were noted, suggesting inhibition of 17, 20 desmolase and 11 beta-hydroxylase enzymes in cortisol biosynthetic pathway.