Regulations of plasma aldosterone in young hyperkalemic patients with stable chronic renal failure.

In a group of four young patients with stable chronic renal failure and hyperkalemia sodium restriction induced a remarkable increase in plasma renin activity (PRA) and plasma aldosterone (PA), a decrease in the elevated serum potassium (SK) and a rise in potassium excretion. During high sodium intake the levels of PRA and PA were lower than those found in the healthy control group suggesting that enhanced suppressibility of the renin-angiotensin-aldosterone system (RAAS) was the main cause of hyperkalemia. During sodium restriction despite a marked increase in PRA and PA levels poor correlations were found between these variables indicating disorganisation within the RAAS and probably a diminished role for renin-angiotensin in the regulation of aldosterone production in three hyperkalemic patients with chronic glomerulonephritis. On the other hand, in the same patients significant correlations were found between fluctuations of SK and PA on constant normal and low sodium diets supporting the concept of an (at least) equal role of potassium and RAAS in the acute regulation of PA. A prominent role for SK was found in an unusual hyperkalemic patient with interstitial nephritis when PRA was suppressed and the elevated SK showed a definite postural rise inducing dramatic increases in PA in the upright posture. Reversion of the postural SK rise masked again the governing role of SK.