Measurement of serum leptin in patients with chronic renal failure on hemodialysis

Background: Leptin, the product of the obese gene, is produced exclusively in fat cells. Subjects, materials and methods: To evaluate the clinical sig nificance of measuring serum leptin in 56 patients with chronic renal failu re on hemodialysis (HD), we measured leptin levels using radioimmunoassay i n 34 normal volunteers and in 56 patients on HD. Results: Normal serum lept in averaged 5.7 +/- 0.7 (mean +/- SEM) ng/ml, which correlated significantl y (p < 0.001) with the body fat percentage as measured by bioelectrical imp edance analysis. Serum leptin in HD patients ranged from 1.3 to 142 ng/ml. The mean serum leptin analyzed after the logarithmic conversion was 5.6 ng/ ml, which was not significantly different from the normal control value, al though the body fat percentage was significantly lower than normal voluntee rs. There was a significant (p < 0.01) positive correlation between body fa t percentage and serum leptin in both normal controls and I-ID patients. Th e slope of the regression curve was steeper in HD patients than in normal c ontrols. Conclusion: (1) serum leptin levels to body fat mass are significa ntly higher in HD patients than controls, (2) the variability is much wider in HD patients; and (3) a significant relation exists between percent body fat and log serum leptin, the relation being steeper in HD patients than i n controls.