Phenylalanine breath test as a method to evaluate hepatic dysfunction in obstructive jaundice

Abstract

Background: The purpose of this study was to investigate whether the hepatic dysfunction associated with obstructive jaundice can be measured from changes in expiratory 13CO2 levels after intravenous administration of l-[1-(13)C]phenylalanine, using a rat model of obstructive jaundice.

Materials and methods: Under pentobarbital anesthesia, bile duct ligation (BDL) was performed (n=12). In the control group, simple laparotomy was performed (n=12). On postoperative day 7, 20 mg/kg l-[1-(13)C]phenylalanine was administered via the femoral vein. Phenylalanine breath test (PBT) was performed for 30 min. We compared single point of 13CO2 level (SPT: T: min) and sum of 13CO2 output (ST) values between BDL and control rats. We examined the correlation of SPT or ST with phenylalanine hydroxylase activity (PHA) and blood chemical parameters.

Results: Both SPT and ST values decreased in BDL compared to control 3 min after the start of PBT (SP10; 103+/-12 (per thousand) versus 84+/-16 (per thousand) P=0.025). PHA/g liver in BDL was significantly decreased compared to control (40.81+/-4.80 (U) versus 28.93+/-9.60 (U) P=0.008). PHA/g liver was correlated with SPT with correlation coefficient of more than 0.715, 10 min after the start of PBT, and the maximum correlation was at SP20 (r=0.801). Blood chemical parameters were correlated with S15 (total bilirubin, r=-0.717; alkaline phosphatase, r=-0.841; gamma-glutamyl transpeptidase, r=-0.759; alanine aminotransferase, r=-0.776; albumin, r=0.819).

Conclusions: In the breath test with intravenously l-[1-(13)C]phenylalanine, hepatic dysfunction associated with obstructive jaundice could be measured in a short period.