Relationship among the concentrations of serum lipoproteins and changes in their chemical composition in patients with untreated nephrotic syndrome

The quantitative and qualitative changes of serum lipoproteins have been studied in twelve patients with untreated uncomplicated nephrotic syndrome. The lipoprotein disorders found in these patients were characterized by an elevation of VLDL (d < 1.006 g ml ‐1 ), LDL (d 1.006–1.019 g ml ‐1 ) and LDL 2 (d 1.019–1.063 g ml ‐1 ) and a diminution of HDL 2 (d 1.063–1.125 g ml ‐1 ). These changes were strictly correlated with the concentration of serum albumin and were more pronounced in the patients with serum albumin < 20 g l ‐1 . The study of the relationship among the concentrations of the various lipoprotein classes indicated that (i) the levels of VLDL and LDL 1 were reciprocally related to that of the high density lipoproteins and (ii) the level of LDL 2 rose with the moderately increased VLDL and LDL 1 but at the high concentrations of VLDL and LDL 1 observed in the severe nephrotic syndrome it did not show any further increase, suggesting a defect in the conversion of VLDL to LDL 2 . The nephrotic syndrome was associated with marked changes in the composition of all lipoprotein fractions which were found to contain more phospholipid but less protein than normal. Major changes in composition were observed in VLDL and LDL 1 which were rich in esterified cholesterol and phopholipids and had an esterified cholesterol: triglyceride molar ratio (CE/TG) higher than the corresponding fractions of the control subjects. Furthermore, CE/TG ratio in these fractions increased as their serum concentration increased. These observations indicate that in severe, untreated uncomplicated nephrotic syndrome there is a progressive accumulation of d < 1.019 g ml ‐1 lipoproteins rich in esterified cholesterol. Chemically these resemble VLDL and chylomicron remnants and are possibly related to some defect in the conversion of VLDL to LDL 2 .