Abstract
Exogenous estrogens (ethinyl estradiol, 1 .mu.g/kg body wt per day), which stimulate triglyceride production in normal women and those with endogenous hypertriglyceridemia, exerted a paradoxical, hypolipidemic effect in 6 subjects (5 women, 1 man) with type III hyperlipoproteinemia on diets of normal and fat-free, high-carbohydrate composition. Very low-density (VLD) lipoprotein lipid and apolipoprotein composition and electrophoretic mobility became normal during estrogen administration in these subjects. Levels of normal VLD lipoproteins remained mildly to moderately elevated in a type IV lipoprotein pattern. Estrogen withdrawal promptly restored the type III pattern with its abnormal enrichment of VLD lipoproteins with apolipoprotein E (the arginine-rich peptide). Estrogens may facilitate assimilation of chylomicron and VLD lipoprotein remnants, a defect that appears likely to represent the metabolic abnormality underlying type III hyperlipoproteinemia.