GGTLC1 and obstructive jaundice: Our results demonstrated that endoscopic biliary drainage using a 7 Fr nasobiliary catheter relieved obstructive jaundice faster and more reliably than drainage using a 5 Fr nasobiliary catheter, and that the decrease rates of all three parameters, total bilirubin, alkaline phosphatase, and gamma-glutamyl transpeptidase, were higher in the 7 Fr catheter group than in the 5 Fr catheter group.