Variations of the renin aldosterone system in Cushing's disease (author's transl)

The renin aldosterone system was studied in 5 cases of Cushing's disease (bilateral benign hyperplasia) without medication. For a daily sodium intake of 120 mmol plasma angiotensinogen was abnormally increased, plasma renin activity (PRA) remained normal, but without significant diurnal variation. Plasma aldosterone (PA) was normal and its circadian rhythm was maintained. One hour active orthostatism and low sodium diet (20 mmol of sodium during 4 days) induced a normal PRA increase but an insufficient PA response. Positive significant correlations were found between PRA and PA and between plasma angiotensinogen and plasma cortisol. The mechanisms underlying this functional hypoaldosteronism were discussed.