INCREASED PLASMA LEPTIN FAT RATIO IN PATIENTS WITH CHRONIC-RENAL-FAILURE - A CAUSE OF MALNUTRITION/

Background. Protein-energy malnutrition occurs in patients with chroni c renal failure primarily due to loss of appetite. The ob gene protein , leptin, which is secreted by adipocytes, regulates body composition by lowering food intake. We have measured plasma leptin in undialysed and dialysed patients and in controls and the concentrations have been related to body composition, dietary intake, and biochemistry. Method s. Plasma leptin was measured by radioimmunoassay in 93 individuals in groups of undialysed, peritoneal dialysed, and haemodialysed patients and controls. Body composition was determined by DEXA. Results. Prote in-energy malnutrition was evident in non-dialysed and dialysed patien ts from low lean or fat tissues, plasma albumin and transferrin. A thi rd of the dialysis patients were eating less than prescribed intakes. Leptin relative to total fat mass (ng/ml/kg) was significantly greater for patients than for controls, particularly the dialysed patients. L eptin was highly correlated with total, arm, leg, and all other fat me asurements, e.g. r for leptin vs% total fat was: undialysed 0.88, PD 0 .81, HD 0.93, and controls 0.83 (P < 0.0001 for all). Dialysis patient s with the highest leptin/fat mass ratio had low protein intakes and s ignificantly lower lean tissue mass. Leptin/fat ratio correlated inver sely with dietary intake e.g, with protein intake in g/day and margina lly in g/kg of ideal weight/day. Leptin concentration was unrelated to plasma creatinine or residual renal function or to the protein 'nutri tional indices', albumin and transferrin. Conclusions. Our data sugges ts that leptin is markedly increased in some patients with chronic ren al failure. The association of increased leptin with low protein intak e and loss of lean tissue is consistent with leptin contributing to ma lnutrition but a definitive role cannot be substantiated by this study .