Serum leptin in end-stage renal disease patients on hemodialysis: its value as a malnutrition marker

ABSTRACT

Leptin is a protein hormone secreted by adipocytes in proportion to the amount of body fat and exerts sustained inhibitory effects on food intake while increasing energy expenditure. It has been reported that serum leptin levels are high in patients with chronic renal failure and may have a potential impact on the development of uremic cachexia. The present study aimed to evaluate serum leptin level and its relation to markers of malnutrition in non diabetic patients with end-stage renal disease [ESRD] treated with hemodialysis. Serum leptin level was measured in 48 ESRD patients [30 males and 18 females] on regular hemodialysis, and in 20 healthy control subjects. The nutritional status was checked by anthropometric measurements [body mass index [BMI] and triceps skin fold thickness [TSFT]] and laboratory data [hemoglobin, hematocrite, serum albumin, pre-albumin, total protein, and blood urea nitrogen]. Patients were included if they were on hemodialysis for more than one year, anuric, had normal C reactive protein values and had no history of diabetes mellitus, liver disease or chronic pulmonary disorders. The mean serum leptin level was higher in ESRD patients [28.5 +/- 15.3ng/ml] compared to the control [5.2 +/- 3.8ng/ml; P<0.001]. The indices of hematological and protein-energy malnutrition were evident in hemodialysed patients compared to controls. The mean serum leptin was significantly higher in male patients compared to the male control group [11.5 +/- 4.7 vs 3.2 +/- 2.1ng/ml, P<0.01]. Also, serum leptin was significantly higher in the female patients compared to the female control group [35.8 +/- 12.1 vs 12.7 +/- 4.5ng/ml, P<0.001]. The mean BMI for female patients was significantly higher than male patients [24.4 +/- 4.1 vs 21.1 +/- 5.6kg/m2, P<0.04]. The mean TSFT for female patients was significantly higher than male patients [13.8 +/- 3.2 vs 10.7 +/- 2.2mm, P<0.05]. A positive correlation was found between the TSFT and leptin, both in male [r=0.44, P<0.03] and female patients [r=0.71, P<0.01]. Also, there was a positive correlation between the BMI and leptin both in male [r=0.41, P<0.02] and female patients [r=0.67, P<0.01]. No correlation was observed between serum leptin with the length of time on dialysis, total protein, serum albumin, pre-albumin, hemoglobin, hematocrite, creatinine and blood urea levels. Serum leptin is markedly elevated in patients with ESRD on hemodialysis. It is significantly correlated with the BMI and TSFT and could be utilized as a potential indicator of malnutrition in these patients. Further studies may provide a therapeutical approach aiming to neutralize serum leptin levels or blocking its effect on the hypothalamus to prevent uremia-associated malnutrition