UCSF

Purpose

Body mass index (BMI) has been shown to influence the outcome of various surgical procedures. The purpose of this study is to assess the relationship between BMI, gender, and the distribution of subcutaneous and perirenal fat.

Methods

A retrospective review was performed for 123 patients who underwent radical or partial nephrectomy. Preoperative CT scans were reviewed by two independent observers. Subcutaneous fat was measured at three locations and perirenal fat was measured at six locations. Statistical analysis was performed using the Student's t test and the Pearson's correlation coefficient.

Results

Mean anterior subcutaneous fat was significantly greater in females than in males (2.54 vs. 1.78 cm, p < 0.001) as was mean right posterolateral subcutaneous fat (2.78 vs. 2.21 cm, p = 0.03). With regard to perirenal fat, men were greater than women for all perirenal locations around the left kidney. For the right kidney, men were greater than women for four out of six perirenal positions. In both men and women, BMI was strongly correlated with subcutaneous fat. However, BMI was weakly correlated with perirenal fat.

Conclusions

Women exceed men in subcutaneous fat, while men exceed women in perirenal fat. Obese patients are very likely to have large amounts of subcutaneous fat, but will not necessarily have proportionally increased fat around their kidneys when compared to the patients with lower BMI. These differences may have important implications for surgical approaches to the kidney.