Captopril in Cushing's syndrome

Abstract

To analyse the role of the renin angiotensin system in the pathogenesis of hypertension in Cushing's syndrome ten patients with hypercorticism (five with pituitary hypothalamic dysfunction, three with adrenal adenomas and two with adrenal carcinomas) received a single oral dose of 25 mg captopril. Mean arterial pressure was then determined at short intervals over periods of up to 240 min. Plasma renin activity (PRA) was measured immediately before the administration of captopril. Eleven patients with severe essential hypertension, who showed a comparable distribution of basal PRA values, served as a control. Patients with elevated basal PRA values (greater than 3 ng/ml X 3 h) showed, both in the subgroup of cases with essential hypertension and in that with Cushing's syndrome, a statistically significant fall (P less than 0.05-P less than 0.001) in mean arterial pressure, the decrease being slightly more pronounced in essential hypertensives. On the other hand patients with normal PRA values (less than or equal to ng/ml X 3 h) exhibited only a minor fall in mean arterial pressure reaching statistical significance (P less than 0.05) only after 60 min (essential hypertension) and 180 min (Cushing's syndrome), respectively. Our results document that in patients with Cushing's syndrome the effect of captopril seems to be determined by the activity of the renin angiotensin system. Thus, in a substantial number of patients with hypercorticism, the renin angiotensin system may be an important factor in the pathogenesis of hypertension, whereas in patients with low PRA values other factors like oversecretion of mineralocorticoids may be responsible for the observed blood pressure increases.