Importance of gamma-glutamyl transferase elevation in patients with Fontan-associated liver disease

Aim: In patients with Fontan-associated liver disease (FALD), gamma-glutamyl transferase (GGT) levels are often elevated, however, its clinical importance is unclear. We investigated the relationship between the clinical course of FALD and GGT levels.

Methods: We enrolled 145 patients with FALD who underwent right-heart catheterization (RHC) and visited our department. Ursodeoxycholic acid (UDCA) was administered to 62 of the patients. Patients with GGT levels <50 and ≥50 U/L were compared. Follow-up RHC was undertaken in 76 patients. Cases in which GGT levels decreased by ≥10% or <50 U/L were defined as improved (n = 33).

Results: Patients with GGT levels ≥50 U/L had significantly lower levels of albumin and higher levels of alanine transaminase (ALT) but no significant differences in RHC factors. Over a 4.6-year period, 43.4% showed improvement in GGT levels. Improved cases had significantly lower total bilirubin (1.1 vs. 1.6 mg/dL), AST (22 vs. 28 U/L), and ALT (18 vs. 27 U/L) levels than nonimproved cases (n = 29, p < 0.05), and the change in platelet count (-0.5 vs. -3.0 × 10^-4/μL) was significantly lower in the latter (p = 0.03). The improvement rate was significantly higher in UDCA-treated cases (55.2%) with GGT levels ≥50 U/L compared to cases not treated with UDCA (18.2%, p = 0.04).

Conclusion: In cases of FALD with no improvement in GGT level, the platelet count decreased over time, suggesting progression of fibrosis. Physicians should be aware of the importance of a high GGT level in patients with FALD.