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


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.
Aoki
Masaru
M
Department of Digestive Surgery, Nihon University School of Medicine, Tokyo, Japan.
Ishii
Yukimoto
Y
Ito
Asuka
A
Khono
Tadashi
T
Takayama
Tadatoshi
T
D000818:Animals; D001835:Body Weight; D001944:Breath Tests / Q000379:methods*; D002245:Carbon Dioxide / Q000378:metabolism; D002247:Carbon Isotopes; D041781:Jaundice, Obstructive / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D008099:Liver / Q000201:enzymology / Q000473:pathology / Q000503:physiopathology; D008107:Liver Diseases / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D008111:Liver Function Tests / Q000379:methods*; D008297:Male; D009929:Organ Size; D010649:Phenylalanine / Q000493:pharmacokinetics; D010651:Phenylalanine Hydroxylase / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
D002247:Carbon Isotopes; D002245:Carbon Dioxide; D010649:Phenylalanine; D010651:Phenylalanine Hydroxylase