Aldosterone related blood volume expansion in cirrhosis before and during the early phase of ascites formation.

Thirty-seven patients with liver cirrhosis (16 without ascites: group 1; 21 with untreated ascites at the first onset: group 2) were studied during controlled sodium intake (40 mmol/day). Renal plasma flow, glomerular filtration rate, urinary sodium excretion, plasma sodium and potassium, plasma renin activity, plasma aldosterone concentration, blood volume, and arterial pressure were evaluated. All the patients had normal renal perfusion, plasma sodium and potassium, and arterial pressure. Mean plasma renin activity and plasma aldosterone concentration were significantly depressed in group 1 (p less than 0.001, p less than 0.005 respectively) compared with 21 normal controls in identical experimental conditions. This was possibly a consequence of expanded blood volume (p less than 0.001 compared with controls) which was directly correlated with plasma aldosterone concentration (p less than 0.001). In group 2 plasma renin activity and plasma aldosterone concentration were normal in over 50% of cases. Blood volume was lower than in group 1 (p less than 0.002), but again related to plasma aldosterone concentration (p less than 0.01). In both groups plasma aldosterone concentration was hyperbolically and inversely correlated with urinary sodium excretion, but the two curves were progressively shifted to the left in respect to controls suggesting an enhanced renal tubular sensitivity to the hormone. The results suggest that aldosterone related renal sodium retention, with consequent blood volume expansion, occurs before ascites formation. The mineralocorticoid activity of aldosterone is amplified by an enhanced sensitivity of renal tubules which appears to increase as the disease progresses.