Leptin is a protein hormone formed mainly in adipocytes and excreted by the kidneys. Hypoleptinaemia is associated with a reduction of body fat percentage and is found in malnutrition and endurance sports. Hyperleptinaemia is found in patients with chronic renal insufficiency and in obese subjects. The authors examined in a group of 80 children (patients with chronic renal insufficiency, malnutrition, obesity and in a control group of healthy children) serum leptin concentrations and compared them with nutritional and anthropometric parameters (BMI, SD, BMI, albumin, prealbumin, transferrin). Significantly higher leptin values were recorded in obese children (p < 0.001) and in children with chronic renal insufficiency (CHRI) as compared with healthy children (p < 0.01). In healthy girls the leptin level was higher than in healthy boys (p < 0.01). Patients with CHRI had higher leptin levels than children after transplantation of the kidneys (p < 0.05). In the group of children with CHRI leptin correlated with creatinaemia (r = 0.479, p < 0.01) and with anthropometric indicators SD BMI (r = 0.693, p < 0.001), BMI (r = 0.653, p < 0.001) and prealbumin (r = 0.385, p < 0.05). In healthy children leptin correlated with SD BMI (r = 0.685, p < 0.01). The authors confirmed higher leptin levels in patients with chronic renal insufficiency and in obese subjects. They conclude that hyperleptinaemia in chronic renal failure is due to impaired leptin elimination by the kidneys.

        Key words: leptin, chronic renal insufficiency, obesity, childhood