Effect of body mass index on serum prostate-specific antigen levels among patients presenting with lower urinary tract symptoms.

Purpose: Studies among asymptomatic male subjects have suggested that a higher body mass index (BMI) is associated with lower serum prostate-specific antigen (PSA) levels. We aimed to investigate whether a similar effect also occurs in patients presenting with lower urinary tract symptoms (LUTS) to a urological unit and its potential implications.

Methods: A retrospective review was carried out at our centre between 2005 and 2009. The serum PSA and BMI of the patients were retrieved from a prospectively collected database. The BMI was divided into normal (< 23 kg/m2), overweight (23-27 kg/m2), and obese (>27 kg/m2) categories according to WHO recommendation for analysis of the association with PSA level.

Results: A total of 1,612 patients with a mean age of 64.6 were included. The mean PSA levels for the normal, overweight, and obese patients were 4.84, 4.54, and 3.95 ng/ml, respectively, with a significant negative correlation (Spearman's coefficient=-0.05, p=0.03). A significant negative association between PSA and BMI among the normal, overweight, and obese groups was also demonstrated by analysis of variance (p=0.01). After adjusting for age differences, there was a significant difference between PSA level for obese patients with a BMI>27 (3.95 ng/ml) and non-obese patients with a BMI<27 (4.67 ng/ml) with analysis of covariance (p=0.02).

Conclusion: In symptomatic male patients, a higher BMI was significantly associated with lower PSA levels. BMI should be considered in the interpretation of serum PSA levels in overweight and obese patients presenting with LUTS.