Cholesterol esterification in plasma as a biomarker for liver function and prediction of mortality

BACKGROUND Advanced stages of liver cirrhosis lead to a dramatically increased mortality. For valid identification of these patients suitable biomarkers are essential. The most important biomarkers for liver function are bilirubin and prothrombin time expressed as International Normalized Ratio (INR). However, the influence of several anticoagulants on the prothrombin time limits its diagnostic value. Aim of this study was the evaluation of cholesterol esterification (CE) fraction (esterified cholesterol vs. total cholesterol) as an alternative biomarker for liver synthesis and mortality prediction. Under physiological conditions the CE fraction in blood is closely regulated by lecithin-cholesterol acyltransferase (LCAT) which is produced in the liver. METHODS One hundred forty-two patients with liver disease clinically considered for orthotopic liver transplant for different indications were enrolled in the study. One patient was excluded because of the intake of a direct oral factor Xa inhibitor which has a strong impact on prothrombin time. RESULTS Results of CE fraction were in good agreement with INR (R(2) = 0.73; p \textless 0.001). In patients who died or survived within three months mean CE fraction was 56% vs. 74% (p \textless 0.001) and mean INR was 2.0 vs. 1.3 (p \textless 0.001), respectively. The predictive value of CE fraction for three-month mortality risk was higher compared to INR (p = 0.04). Results for one-year mortality were comparable. CONCLUSIONS The cholesterol esterification fraction is a valid biomarker for liver synthesis and allows reliable prediction of mortality. In contrast to INR, it is independent of anticoagulation and other analytical limitations of coagulation tests.