In this study, conducted on a representative sample of the general, non-institutionalized U.S. population, we identified a significant inverse correlation between PPI use and PSA values, after controlling for all available clinically meaningful regressors (age, race/ethnicity, BMI, concomitant therapy, diabetes, history of BPE) and excluding subjects with ongoing conditions affecting PSA levels (history of PCa, urinary tract infection, recent invasive maneuvers on the urinary tract). Here, KLK3 is linked to urinary tract infection.