Establishing "Normal" Values for Liver Function Tests after Reconstruction of Biliary Injuries

Background: Abnormalities of liver function tests (LFT) are sometimes taken as evidence of a less than optimal result after repair of a biliary injury. Rather than indicating liver or anastomotic dysfunction, moderate LFT elevations can be "normal" for these patients. This study's aim was to determine LFT reference values after biliary-enteric anastomosis for biliary injury repair in persons who have had an excellent postoperative course for > 6 months. Study Design: Of 113 patients repaired, 73 were identified with the following characteristics: LFT available at ≥ 6 months after repair, no biliary tract symptoms, no underlying liver disease, and biliary injury sustained during cholecystectomy. Outside LFT results were standardized to Barnes-Jewish Hospital reference values. One set of LFT per patient was collected at the following times points after repair: 6 months to 2 years, 2 to 5 years, and > 5 years. Results: For each distribution, the 97.5^th p97.5ercentile values for alkaline phosphatase (≥ 166 IU/L) and total bilirubin (≥ 1.3 mg/dL) were elevated relative to Barnes-Jewish Hospital standard values. Values for alanine aminotransferase and aspartate aminotransferase were more variable. Conclusions: Moderate LFT elevations exceeding standard reference values are common after repair of a biliary injury in patients who have had excellent results. Alkaline phosphatase values fall with time after repair so that comparisons should take into account time from repair. Values ≤ 97.5^th percentile limits described here should not be taken as evidence of liver or anastomotic dysfunction.