Hyperlipemia is a common manifestation of the nephrotic syndrome. Serum lipid concentrations have been observed by others to be negatively correlated with serum protein concentration. Hyperlipemia has been postulated to result from a coordinate increase in the synthesis of both albumin and lipoproteins, as well as from their decreased catabolism. Simultaneous measurements of serum lipid concentration and the rate of albumin synthesis have not been previously reported. We measured the rate of albumin synthesis, urinary albumin loss, serum albumin, protein, cholesterol and triglyceride concentration in 13 nephrotic patients. Changes in the rate of albumin synthesis and in urinary albumin excretion were induced in eight patients by alteration in dietary protein intake. The resultant changes in serum triglyceride and cholesterol were analyzed by multiple regression analysis. The rate of albumin synthesis measured while patients were eating a low protein diet was 12.61 ± 1.20 g/1.73 m2/day, well within normal limits, yet both serum triglyceride and cholesterol concentrations were markedly elevated (265 ± 65 mg/dl and 325 ± 44 mg/dl, respectively). Albumin synthetic rate increased to 17.60 ± 1.25 g/1.73 m2/day when dietary protein intake was increased, while serum triglyceride and cholesterol concentrations changed little; triglyceride concentration was 306 ± 75 mg/dl and cholesterol 376 ± 55 mg/dl. Serum cholesterol concentration, by multiple regression analysis, was dependent only upon the renal clearance of albumin P < 0.0001, and changes in serum cholesterol concentration was dependent only upon changes in the renal clearance of albumin, P < 0.001. Serum cholesterol concentration was completely independent of the rate of albumin synthesis. Serum triglyceride concentration was also primarily dependent upon the renal clearance of albumin, r2 = 0.663 P < 0.0001, with some contribution by the rate of albumin synthesis, r2 = 0.112, P = 0.028. Changes in serum triglyceride concentration were also dependent upon changes in the rate of albumin synthesis, r2 = 0.624, P < 0.002. We could find no evidence for a relationship between hypercholesterolemia and the rate of albumin synthesis in nephrosis. While serum triglyceride concentration showed some correlation with the rate of albumin synthesis, the very fact that the rate of albumin synthesis was only modestly increased, if at all, while serum triglyceride concentration was grossly elevated, made it unlikely that there was a direct link between albumin synthesis and that of either triglycerides or of apolipoproteins. These data suggest that the renal loss of macromolecules, either albumin, or other substances cleared by the kidney in a parallel fashion with albumin, play a role in the deranged cholesterol metabolism in nephrosis, and perhaps also contribute to derangements in triglyceride metabolism in these patients as well.
|Original language||English (US)|
|Number of pages||9|
|State||Published - 1987|
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