Introduction:
The aim of this study was to answer the question what the dependence of glomerular filtration rate from the body mass index and waist circumference is.

Material and Methods:
The study included 48 men aged 18–30, 19 of which (40%) had normal weight, 15 (31%) – were overweight, and 14 (29%) were obese (n = 14). 25 men (52%) had waist circumference less than 94 cm, 8 men (16%) in the range 94-102 cm, and 15 (32%) had greater than 102 cm. Their height, weight, waist circumference, serum creatinine, BMI, were measured using GRF MDRD equations and Cockcroft-Gault equation.

Results:
GFR estimated by the Cockcroft-Gault equation in men with normal body weight was 124.5 ml / min ± 19.5 ml / min, with overweight – 156.7 ml / min ± 29.3 ml / min, with obesity – 215.1 ml / min ± 61.6 ml / min. GFR estimated by MDRD equation was: 107.5 ml / min ± 13.5 ml /min, 112.4 mL / min ± 17.4 ml / min, 115.1 mL / min ± 21.0 ml / min. GFR estimated by the Cockcroft-Gault equation in men with waist circumference < 94cm was 126.4 ml / min ± 18.7 ml / min, with waist circumference 94-102 cm – 169.3 ml / min ± 20.2 ml / min and with waist circumference> 102 cm - 214.2 ml / min ± 60.2 ml / min. GFR estimated by MDRD formula respectively was 106.4 ml / min ± 13.4 ml / min, 119.5 mL / min ± 13.5 ml / min, 114.8 mL / min ± 22.1 ml / min. Signifi cant diff erences between groups occurred only after application of the Cockcroft-Gault equation.

Conclusions:
The results of this study support the assertion that the MDRD formula is more credible than the Cockcroft-Gault equation to assess renal function in patients with overweight and obesity, including abdominal obesity.