Hyponatremia in liver cirrhosis: pathophysiological principles of management

BACKGROUND: Hyponatremia represents a frequent complication of liver cirrhosis, associated with adverse events and death. It is caused either by excessive water retention or solute depletion, or a combination of both. AIMS: To determine the cause of hyponatremia clinically and to examine the usefulness of quantitative calculations of water excess and Na deficit to guide treatment. METHODS: We studied 23 patients with liver cirrhosis and PNa < or =131 meq/L to determine the cause of hyponatremia and results of quantitative treatment. RESULTS: The most frequent cause of hyponatremia was diuretic-induced Na depletion, which occurred in 14 out of 23 instances, while four patients had water excess. Hyponatremia was corrected after a quantitative estimate of the Na deficit or relative water excess by algebraic formulas. The former was quantitatively replenished as 3% NaCl, the latter was excreted with the technique of furosemide-induced diuresis and re-infusion of solute, but not water, losses. After quantitative replacement, there was a significant correlation (R=0.98, P< 0.001) between the Na concentration predicted mathematically and that actually measured. CONCLUSIONS: The hyponatremia of cirrhosis is frequently caused by diuretics. Its treatment can be effectively guided with the aid of quantitative estimates of Na deficit and/or water excess in all instances, although the methods of correction described are indicated in severe clinical conditions.