Introduction

Obesity is a known risk factor for kidney donors to develop chronic kidney disease. The Framingham heart study suggested that visceral adipose tissue (VAT) confers a more adverse metabolic profile compared with subcutaneous adipose tissue (SAT). Asians tend to have a higher VAT composition and it is unclear if their kidney function is affected differently. We hypothesized that living kidney Asian donors who have visceral obesity are at higher risk of renal function deterioration 1 year after donation.

Methods

Between 2011 and 2014, we retrospectively evaluated data from 73 consecutive patients (52% male; mean age 44.9±11.7years) before they underwent donor nephrectomy and at their 1 year routine follow up. VAT and SAT were measured at the level of the umbilicus on preoperative computerized tomography (CT). Visceral obesity (VO) was defined as a VAT >100cm² and patients were then further examined in 2 subgroups: VAT>100 and <100cm². Estimated glomerular filtration rate (eGFR, mL/min per 1.73m²) was calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation preoperatively and 1 year postoperatively.

Results

Both subgroups demonstrated similar kidney function (P=NS) preoperatively. At the 1 year follow up, patients with VO experienced a more significant decline of renal function (109±9 to 89±8 mL/min per 1.73m²), compared to those without VO (111±12 to 96±11 mL/min per 1.73m², P =0.013). VO was associated with a body mass index (BMI) >25 kg/m² (P <0.001), male gender (P <0.001) and older age at the time of donor nephrectomy (48.0 vs 39.5 years, P =0.01). The presence of hypertension or hyperlipidemia preoperatively, choice of surgical approach, and post-operative complication rates, did not differ significantly between the subgroups.

Conclusions

Visceral obesity as defined by VAT >100cm² at the level of the umbilicus on cross-sectional imaging, significantly impacts on renal function after donor nephrectomy. We suggest that adiposity markers, as measured by cross-sectional CT imaging, be incorporated into routine pre-operative kidney donor workup.

Funding

None