In a study of 26 patients with cirrhosis, plasma norepinephrine concentrations were significantly higher in 19 patients who abnormally excreted an acute water load than in seven who excreted the load normally (8324 +/- 116 vs. 306 +/- 33 pg per milliliter; P less than 0.001). There was also a significant positive correlation between plasma levels of norepinephrine and arginine vasopressin after the water load, as well as a negative correlation between plasma norepinephrine and the percentage of the load excreted. A positive correlation between plasma norepinephrine and plasma renin activity, as well as between norepinephrine and aldosterone, was observed. In addition, there was a negative correlation between plasma norepinephrine and urinary sodium excretion. These findings indicate that increased sympathetic activity, as assessed by plasma levels of norepinephrine, correlates closely with sodium and water retention in cirrhotic patients and thus may be of pathogenetic importance.