Serum lipid and lipoprotein alterations in nephrosis.

When nephrosis was recognized as a clinical entity, an increased concentration of serum cholesterol was observed to be a consistent feature of the syndrome (1). Later it was found that phospholipid and triglyceride also are increased in nephrosis (2-5). The increase in serum lipids in nephrosis is usually greatest in the cases with the lowest levels of serum albumin. It has not been established conclusively, however, that the hyperlipidemia is caused by hypoalbuminemia, and irregularities in the relationship between levels of serum lipids and serum albumin have been pointed out repeatedly (2-5). After it was recognized that lipids exist in the serum in the form of lipoprotein macromolecules, techniques developed for the separation and characterization of proteins were applied to studies of lipoproteins. An abnormal distribution of cholesterol among the serum protein fractions precipitated by alcohol was found by Barr, Russ and Eder (6) in cases of nephrosis. Kunkel and Slater (7) observed an abnormal pattern of serum lipoproteins by zone electrophoresis-in part a result of increased quantities of unesterified fatty acid bound to the lipoproteins (8)-in nephrosis. Gofman, Rubin, McGinley and Jones (9) noted in nephrotic subjects that all classes of lipoproteins studied by them in the analytical ultracentrifuge (Sf 0 to 400) were increased. In the present study lipoprotein fractions of sera from patients with nephrosis were isolated by the technique of ultracentrifugation at various densities and analyzed for lipids and protein. Levels of individual serum lipids are correlated with lipoprotein pattern, and also with serum lactescence and serum albumin concentration. It is emphasized that lipoprotein patterns of different sera may differ greatly even when serum cholesterol levels are the same. METHODS