ROLE OF VASOPRESSIN IN ABNORMAL WATER-EXCRETION IN CIRRHOTIC-PATIENTS

Twelve stable cirrhotic patients with ascites received a 20 ml/kg H2O load. Seven patients had abnormal H2O excretion (27.3% .+-. 5.4% of the H2O load in 5 h) and a minimal urine osmolality of 262 mosmol/kg H2O. Five patients excreted 82.6% in 5 h and had a minimal urine osmolality of 65 mosmol/kg H2O. Mean plasma arginine vasopressin values after H2O load were significantly higher in Group 1 (1.34 .+-. 0.36 pg/ml) than in Group 2 (undetectable). An effective blood volume lower in Group 1 than Group 2 patients was suggested by a lower plasma albumin (2.5 vs. 3.3 g/dl, P < 0.02), a higher pulse rate (96 vs. 72, P < 0.001) a higher plasma renin activity (7.8 vs. 1.5 ng/ml per h, P < 0.005), a higher plasma aldosterone (66 vs. 21 ng/dl, P < 0.05), and a lower urinary Na excretion (2.7 vs. 14.2 meq Na/5 h, P < 0.005). Nonosmotic stimulation of vasopressin secondary to a decrease in effective blood volume is an important factor in the abnormal H2O excretion in cirrhosis.