Evaluation of Enzymatic Liver Function Using Liver Maximum Capacity Test (LiMAx) in Adult Fontan Patients

Background: The Fontan-associated liver disease (FALD) is the most common end-organ dysfunction affecting up to 70 to 80% of the Fontan population. The clinical significance of FALD is incompletely understood and no unambiguous correlation of hepatic function with FALD severity has been established. In this study, we sought to evaluate enzymatic liver function with liver maximum function capacity test (LiMAx) in adult Fontan patients.

Method: Thirty-nine adult Fontan patients (median age: 29.4 years [IQR: 23.4; 37.4], median follow-up after Fontan operation: 23.9 years [IQR: 17.8; 26.4]) were analyzed in a cross-sectional observational study using LiMAx test, laboratory testing, transient elastography (TE), and hepatic ultrasound. The LiMAx test is based on the metabolism of 13C-methacetin which is administered intravenously and cleaved by the hepatic cytochrome P4501A2 to paracetamol and 13CO₂ being measured in the exhaled air and corresponding to a quantitative measurement of maximal liver function capacity.

Results: Hepatic enzymatic function assessed by the LiMAx test was normal in 28 patients (>315 µg/h/kg) and mild to moderately impaired in 11 patients (140–314 µg/h/kg). No patient suffered from severe hepatic damage (<139 µg/kg/h). Interestingly, no correlation was found between the assessed metabolic liver function and TE (r ² = −0.151; p = 0.388) or the number of sonographic abnormalities suggestive of FALD (r ² = −0.204, p = 0.24). There was, however, an association between enzymatic liver function capacity and the laboratory parameters bilirubin (r ² = −0.333, p = 0.009) and γ-glutamyl transferase (γGT). No correlation was detected between maximal liver function capacity and the severity of FALD (r ² = −0.235; p = 0.152).

Conclusion: This is the first study to evaluate enzymatic liver function using the LiMAx test in adult Fontan patients. In the majority of our patients, maximum liver capacity was preserved despite sonographic and serological evidence of FALD and did not significantly correlate with FALD severity.

Publication History

Article published online:
12 February 2022