Plasma renin activity and plasma aldosterone in acute renal failure

Plasma renin activity and plasma aldosterone were determined by radioimmunoassay methods in 20 patients in oliguric phase, in 11 patients in polyuric phase and in 7 patients in convalescent phase of acute renal failure of various origin. The oliguric phase of acute renal failure was characterized by significant increase of plasma renin activity and plasma aldosterone. There was no direct dependence between them. Direct dependence was found between plasma aldosterone and serum potassium in the oliguric phase of acute renal failure, indirect dependence between plasma aldosterone and serum sodium was found before as well as after haemodialysis. These findings prove a direct influence of hyperkalemia and depletion hyponatremia upon aldosterone secretion in the oliguric phase of acute renal failure. Haemodialysis led to a further increase of plasma renin activity caused by ultrafiltration as well as successive dehydration and application of some drugs. The mean value of plasma aldosterone was not significantly changed after haemodialysis. Plasma renin activity decreased very slowly in the polyuric and convalescence phase of acute renal failure, while plasma aldosterone concentration was already in polyuric phase non-significantly different from the control group. There was no direct dependence in the various phases of acute renal failure between plasma renin activity, plasma aldosterone, systolic and diastolic pressure.The renin-angiotensin-aldosterone system significantly participates in the pathogenesis of acute renal failure in man, but various causes of acute renal failure, different drugs, as well as therapeutic procedures do not make it possible to quantify it in detail.Charcoal haemoperfusion in acute poisonings led only to non-significant increase of plasma renin activity and decrease of plasma aldosterone.