Protein C activity and postoperative metabolic liver function after liver transplantation

Background. Protein C is a natural thrombin antagonist produced by hepatocytes. Its levels are low in liver failure and predispose patients to increased risk for thrombosis. Little is known about the relationship between protein C activity and hepatic function after orthotopic liver transplantation (OLT). Methods. We measured protein C activity of 41 patients undergoing liver transplantation by the Staclot method (normal range, 70%-130%) preoperatively and then daily on postoperative days (POD) 0-5. Results. The mean protein C activity was low before OLT (34.3 ± 4.3%) and inversely correlated with the preoperative Model for End-Stage Liver Disease score (Spearman's r = -0.643; P < .0001). Mean activity increased significantly on POD 1 (58.9 ± 4.5%), and remained above preoperative levels through POD 5. Ten patients developed metabolic liver dysfunction defined by a serum total bilirubin >5 mg/dL on POD 7. These patients had significantly lower protein C activity from POD 3 (47.2 ± 9.6% vs 75.9 ± 5.8%; P = .01) to POD 5. Preoperative protein C activity correlated inversely with the severity of liver failure as indicated by preoperative MELD score. Conclusion. Protein C activity recovered rapidly in patients with good allograft function but remained significantly lower in patients who had limited metabolic function as evidenced by increased total bilirubin levels.