Lipoprotein X in autoimmune liver disease causing interference in routine and specialist biochemical investigations

Abstract

AbstractPrimary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC) are chronic, immune-mediated diseases which may be associated with the presence of lipoprotein X (LpX). This is an abnormal lipoprotein resulting in marked elevation of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) concentration. LpX is rich in free cholesterol (FC) and phospholipids (PL) and low in esterified cholesterol (CE). We describe two cases with florid lipid stigmata and presence of LpX. A patient with PBC presented with itching and palmar xanthomata. TC = 55.5 mmol/L, direct LDL-C = 14.9 mmol/L, high-density lipoprotein cholesterol (HDL-C) = 0.5 mmol and triglycerides (TG) = 11.3 mmol/L. Lipoprotein electrophoresis (LPE) showed the presence of LpX. An apolipoprotein E (Apo E) phenotype and genotype reported E2E3 and E3E3 isoforms, respectively. A patient with PSC presented with itchy eruptive xanthomata. TC = 22.8 mmol/L, calculated LDL-C = 21.7 mmol/L, HDL-C = 0.2 mmol/L and TG = 1.6 mmol/L...