Gamma-glutamyl transferase in the diagnosis of biliary atresia

Early diagnosis of biliary atresia (BA) is important because the prognosis is closely related to timing of Kasai operation. The aim of this study was to test the clinical application of serum gamma-glutamyl transferase (GGT) concentration and the ratio of serum GGT to aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in differentiating BA from neonatal hepatitis (NH).

Ninety-three (46 male and 47 female) cases of BA and 65 (45 male and 20 female) NH were included in this study. Serum concentrations of GGT, AST, and ALT were measured in all cholestatic infants. The results of peak GGT level, GGT/AST ratio, GGT/ALT ratio were compared between groups.

The serum GGT levels were significantly higher in BA patients than those in NH patients (353.3 +/- 334.4 IU/L vs. 114.8 +/- 86 IU/L, P < 0.001). GGT/AST values were over 2 in 55/68 BA and 15/ 54 NH (OR = 11.0, 95% CI 4.7-25.7, P < 0.001). GGT/ALT values were over 2 in 54/65 BA and 19/50, NH respectively (OR = 8.0, 95% CI 3.4-19.0, P < 0.001). A GGT level greater than 300 IU/L had a sensitivity of 39.7% in the diagnosis of BA, GGT/AST over 2 was 80.9% and GGT/ALT over 2 was 83.1%; the specificities were 98.1%, 72.2% and 62.0%, respectively. The respective accuracies of the diagnosis of BA were 65.6%, 77.1% and 73.9%.

GGT/AST ratio over 2 indicates high possibility of biliary atresia and should prompt further investigations to confirm the diagnosis.