Constipation has been identified as a factor that affects PSA levels in men. Bayraktar et al. showed that serum total PSA levels were significantly higher in constipated patients (n = 136) compared to control patients (n = 45) (2.29 ± 1.29 ng/ml versus 1.28 ± 0.86 ng/ml, P <0.0001). After treating constipation, this difference was no longer significant. Constipation should be treated before a PSA measurement is obtained, and should be considered in patients with borderline high serum PSA.