Lipoprotein-X (Lp-X) is an abnormal
low-density lipoprotein frequently found in
liver disease. It is regarded as the most sensitive and specific biochemical parameter for the diagnosis of intra- and
extrahepatic cholestasis. Moreover, Lp-X is supposed to contribute to the development of
hypercholesterolemia in cholestatic
liver disease, because it fails to inhibit de novo
cholesterol synthesis. This investigation will focus on the relationship between the presence of Lp-X and serum
lipid concentrations in
cirrhosis. The significance of Lp-X in the diagnosis of
cholestasis, compared with
alkaline phosphatase (AP), gamma-glutamyl
transferase (GGT), and
bilirubin levels, will be assessed as well. The present cross-sectional study includes 212 patients with histopathologically proven
cirrhosis. The detection of Lp-X and the quantification of -, beta-, and pre-beta-
cholesterol was based on
agar gel electrophoresis and polyanion precipitation. For the characterization of liver function, the concentrations of
albumin and
bilirubin, the activities of liver
enzymes, and coagulation times were assessed. In a subgroup of 40 individuals, liver biopsies were re-evaluated to confirm or exclude
intrahepatic cholestasis. As a result, there was no association between the appearance of Lp-X and total
cholesterol concentrations. While all patients with Lp-X showed
intrahepatic cholestasis (predictive value of the positive test = 1), only 16 of 28 patients with
cholestasis formed Lp-X (sensitivity = 0.57). The activities of AP and of GGT, as well as the concentrations of
bilirubin, were strongly elevated in most patients, with and without
cholestasis. The predictive values of AP, GGT, and
bilirubin were 0.77, 0.69, and 0.74 for the positive test and 0.5, 0, and 0.6 for the negative test, respectively. We conclude that Lp-X is not related to
hypercholesterolemia in
cirrhosis. The positive, but not the negative, Lp-X test has high predictive value for the diagnosis of
cholestasis in
cirrhosis. The biochemical parameters traditionally used for the assessment of
extrahepatic cholestasis, AP, GGT, and
bilirubin, do not support the diagnosis of
intrahepatic cholestasis caused by
cirrhosis.