Serum Cholesterol Esterification in Liver Disease. Combined Determinations of Lecithin: Cholesterol Acyltransferase and Lipoprotein‐X

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Abstract
Indirect evidence suggests that lecithin:cholesterol acyltransferase (LCAT) is synthesized in the liver. There are, however, controversial reports in the literature correlating LCAT activity with various forms of liver disease. The purpose of this study was to determine LCAT activity in icteric patients. These were classified not only by the conventional methods, but also with respect to the presence or absence of LP‐X, an abnormal plasma lipoprotein, highly specific for demonstrating or excluding cholestasis. LCAT was measured at different stages of the disease. The patients were divided into 4 groups: I. Hepatitis with cholestasis (LP‐X pos.) [17]; II. Hepatitis without cholestsis (LP‐X neg.) [12]; III. Extra‐hepatic biliary obstruction (LP‐X pos.) [10]; IV. Chronic liver failure (LP‐X neg./pos.) [11]. Compared to normal controls [15], patients from group I had low, group II had normal, group III had normal and group IV had low LCAT activity. In vitro studies clearly excluded the existence of circulating inhibitors of LCAT. From these data it is suggested that the ratio of esterified to unesterified cholesterol in liver disease depends on two factors: LCAT activity and the occurrence of the abnormal lipoprotein‐X. Furthermore these results indicate that combined determinations of LCAT and LP‐X may prove to be useful techniques for differentiating intra‐ and extra‐hepatic cholestasis.