Clinical and hormonal conditions associated with sodium retention in cirrhotic patients with ascites. Evaluation by univariate and multivariate analyses

Using multiple regression analysis, we have evaluated the clinical and hormonal conditions associated with impaired urinary sodium excretion in normoazotemic patients with cirrhosis and ascites. We retrospectively identified 13 patients with a urinary sodium excretion lower than 15 mmol/day and 13 patients with a sodium excretion higher than 15 mmol/day. Using univariate analysis, all the patients with poor sodium excretion had abnormally high levels of plasma renin activity, plasma aldosterone, and arginine vasopressin. In addition, they had a diastolic blood pressure lower than patients with high urinary sodium excretion, although otherwise were comparable as regards clinical and biochemical data. The consistency of the above associations was then tested by multiple-regression analysis in an attempt to control for potentially confounding factors and to identify only true, independent associations. After a discriminant stepwise procedure, we found that low diastolic blood pressure (P less than 0.01) and high plasma aldosterone levels (P less than 0.05) were the only two conditions independently associated with abnormally low urinary sodium excretion. These findings are consistent with the view that sodium retention in decompensated cirrhosis results from a concomitant severe contraction in the effective blood volume and an increased production and/or retention of aldosterone. The concordance between our results and several pathophysiological findings supports the validity of this statistical approach to confirm physiological and/or clinical predictions.