Increased glomerular filtration rate and adrenocortical function in obese women

Glomerular filtration rate (GFR) was measured in 16 obese women aged 28-48 years (overweight 65-110 per cent) and compared to GFR in 16 non-obese women of the same age and height. None of the women had signs of nephrourological disorders. GFR was determined from the total 51 Cr-EDTA plasma clearance measured by a simplified single-injection technique. In the obese women GFR (median value 129.0 ml/min) was significantly (P less than 0.002) increased by 24.6 per cent. The urinary excretion rate of 17-ketogenic steroids was increased in nine out of 14 obese women, but no correlation with GFR could be demonstrated. GFR in the obese women showed a significant positive correlation with the plasma cortisol concentration (rs = 0.77; P less than 0.01) and with the urinary excretion rate of free cortisol (rs = 0.78; P less than 0.01). Whether the correlation between the plasma cortisol concentration and the increased GFR in obese women is causal needs further investigation.