Effects of peritoneovenous shunting on body composition

The effect of peritoneovenous shunting on body composition has been studied in 7 cirrhotic patients undergoing a successful shunt and 3 patients in whom the shunt was unsuccessful. In the 7 patients with functioning shunts, their weight had decreased by a mean of 9 kg (p less than 0.001) by 6 wk after initial diuresis, natriuresis, and kaliuresis, and was associated with a decrease in total body potassium (TBK) but not total body nitrogen (TBN). This resulted in a significant decrease in the TBK/TBN ratio from 2.12 +/- 0.74 to 1.66 +/- 0.20 (p less than 0.01). By a mean of 14 mo, in these 7 patients there was a significant increase in mean TBN (from 1.54 +/- 0.10 to 1.84 +/- 0.10, p less than 0.005) associated with an improvement in the mean nitrogen index (from 0.74 +/- 0.04 to 0.88 +/- 0.04, p less than 0.005). These changes were associated with a significant increase in nonalcoholic calories, a nonsignificant increase in protein consumption, and a positive nitrogen balance. After the initial kaliuresis, mean potassium balance remained constantly positive (+22.7 +/- 3.4 mmol/day), serum aldosterone levels normalized, and TBK increased. In contrast, 3 patients with failed peritoneovenous shunting continued to lose weight significantly despite the presence of ascites; TBN and nitrogen index also decreased. In conclusion, body composition studies appear to have confirmed the clinical observation that cirrhotic patients with massive ascites have depleted body protein which is gradually repleted only after successful shunting. In this situation TBK, long used as a measure of lean body mass, is less satisfactory than TBN and nitrogen index. This improvement in body protein appears to be explained by an increased dietary intake associated with improved nitrogen balance, but these changes are not found in patients in whom the shunt failed.