Albumin synthesis, albuminuria and hyperlipemia in nephrotic patients

Abstract

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 less than 0.0001, and changes in serum cholesterol concentration was dependent only upon changes in the renal clearance of albumin, P less than 0.001. Serum cholesterol concentration was completely independent of the rate of albumin synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)