Glomerular filtration rate in severely overweight normotensive humans

The study examined whether indexing glomerular filtration rate (GFR) for bo dy surface area is appropriate for people who are severely overweight. Twen ty normotensive adult men who were severely overweight but without microalb uminuria were enrolled into this study. The control group consisted of 20 h ealthy subjects matched for age, sex, and height. GFR was determined by mea suring insulin with the continuous-infusion method. The clearance of endoge nous creatinine was also measured after two daily urine collections. Renal plasma flow (RPF) was measured by p-aminohippurate clearance using the cont inuous-infusion method. Lean body weight was measured by impedentiometry. A djusting for body surface area (in 1.73 m(2)) caused a significant reductio n in GFR (P < 0.0001) in overweight humans(84.1 +/- 2.32 versus 109.6 +/- 3 .07 mL/min/1.73 m(2)). The difference disappeared when GFR/height criteria were adopted. No difference between obese and healthy controls occurred aft er adjusting for lean body weight. Data for creatinine clearance paralleled those with insulin clearance; a significant reduction (P < 0.001) occurred after indexing for basal surface area, which disappeared after correction for height, as well as for lean body weight. (C) 2000 by the National Kidne y Foundation, Inc.