The renin-aldosterone system and thiazide-induced depletion of total body potassium in essential hypertension.

15 patients who had benign, uncomplicated essential hypertension, were treated with chlorthiazide (500 mg twice a day) with or without propranolol (10--20 mg 4 times a day), and the effect of the treatment on plasma renin activity (PRA), urinary aldosterone excretion, total body potassium (TBK) and plasma sodium and potassium was evaluated. TBK depletion was significant mathematically (more than 5% of TBK lost) in 7 patients, but not significant physiologically (less than 15% of TBK lost) in any except in one, who may have had other reason for TBK depletion. Although propranolol prevented the increase in PRA and aldosterone excretion, it did not prevent the modest TBK depletion. Dietary potassium intake may have some importance in the maintenance of normal body potassium during chronic treatment with thiazides for hypertension.