Increased Low-Density-Lipoprotein Catabolism in Myeloproliferative Disorders

Abstract

Hypocholesterolemia reported in patients with myeloproliferative disorders prompted an investigation of lipoprotein metabolism in these patients. The production and fractional catabolic rates of very-low-density lipoprotein (VLDL) apoprotein-B were measured using 131I-VLDL; those of VLDL triglyceride, using 3H-glycerol; and those of low-density lipoprotein (LDL) apoprotein-B, using 125I-LDL. Plasma total and LDL cholesterol levels (mean .+-. SD) were significantly reduced in 7 patients with myeloproliferative diseases, compared to 5 normal subjects (93.1 .+-. 20.3 mg/dl vs. 166.8 .+-. 24.6 mg/dl and 50.3 .+-. 14.8 mg/dl vs. 107 .+-. 20.8 mg/dl, respectively). The production rates of VLDL apoprotein-B and VLDL triglyceride were normal in the patients. The fractional catabolic rate of LDL apoprotein-B was increased in the patients with myeloproliferative diseases (0.89 .+-. 0.32/d [day] vs. 0.52 .+-. 0.10 d;P < 0.05); this increased rate was associated with reduced plasma LDL apoprotein-B levels (41.7 .+-. 7.1 mg/dl vs. 57.0 .+-. 11.3 mg/dl; P < 0.05) despite normal or elevated LDL apoprotein-B production (16.7 .+-. 5.3 mg/kg body wt d vs. 12.9 .+-. 1.2 mg/kg body wt d). The site (or sites) of increased LDL catabolism in these hypocholesterolemic patients with myeloproliferative disorders is under investigation.