A Study of Renal Outcomes in Obese Living Kidney Donors

Background. Little is known about the long-term outcomes of obese living kidney donors (OLKDs). We undertook this study to describe renal outcomes of OLKDs several years after donation. Methods. We invited 101 OLKDs for follow-up health evaluation. Results. Thirty-six subjects (35.6%) completed evaluation at 6.8 +/- 1.5 years postdonation. The mean estimated glomerular filtration rate (eGFR) using the abbreviated modification of diet in renal disease (MDRD) equation (MDRD-eGFR) at follow-up was 72.1 +/- 16.3 (range: 42-106) mL/min per 1.73 m(2), and 47.2% of subjects had an MDRD-eGFR of 30 to 59. The absolute decrease in MDRD-eGFR from the time of donation to follow-up was 27.2 +/- 13.1 mL/min per 1.73 m(2) (P<0.001 on paired t test), which represents a 29.2% drop in the serial MDRD-eGFRs. Seven subjects (19.4%) had microalbuminuria (30-300 mu g/mg creatinine). Subjects with microabuminuria were more likely to have MDRD-eGFR of less than 60 mL/min per 1.73 m(2) (P=0.021). Subjects whose body mass index was greater than or equal to 35 kg/m(2) (n=14) were found to have an absolute decrement in MDRD-eGFR similar to those with body mass index less than 35 kg/m(2) (31.5 +/- 15.6 and 24.7 +/- 11.0 mL/min/1.73 m(2), respectively; P=not significant). Fifteen (41.6%) were hypertensive at follow-up. Conclusions. On medium-term follow-up, a large proportion of OLKDs will have a MDRD-eGFR of less than 60 mL/min per 1.73 m(2), and the likelihood increases markedly among those who develop microalbuninuria. This raises concern for hyperfiltration injury. Furthermore, OLKDs experience a substantial incidence of hypertension. Caution is advised in selecting OLKDs pending further data on long-term outcomes.