Relationship of plasma aldosterone concentration to electrolytes and acid-base balance in blood after open cardiac surgery.

Plasma aldosterone concentration was measured in 11 cardiac patients after open cardiac surgery, by the radioimmunoassay method, and the relationship of it to electrolytes and acid-base balance of blood was analyzed. Plasma aldosterone concentration was markedly elevated in patients with low cardiac output, who required postoperative drip infusion of Isoproterenol, and in addition, both remarkable metabolic alkalosis and increase of potassium excretion in urine were confirmed in these patients. Plasma aldosterone concentration correlated significantly with potassium excretion in urine and was inversely related with potassium balance. However, plasma potassium concentration or arterial pH had no correlation to it. Approximately an inverse correlation was found between the logarithm of the sodium/potassium ratio in urine and plasma aldosterone concentration. These data indicate that aldosterone is an important factor which produces potassium depletion after open cardiac surgery.