Introduction and Objective: The objective of this study was to evaluate the impact of age and prostate volume on the PSA response to testosterone replacement therapy (TRT).
Methods: A retrospective study was performed of 269 symptomatic hypogonadal men who underwent TRT for a minimum of 3 months. All men presented with erectile dysfunction (ED) and/or diminished libido, and had total testosterone (TT) <300ng/dl, and/or free testosterone (FT) <1.5 ng/dl. Serum testosterone levels and PSA were evaluated at baseline for all men and at 3 months follow-up. The entire group was divided by age: Group 1:<50 yrs (N=82); Group 2: 50-59 yrs (N=103);Group 3: 60-69 yrs (N=62); Group 4:>70 yrs (N=22). In addition, 218 of these men underwent trans-rectal ultrasound and prostate biopsies prior to TRT. Men with prostate cancer were exclused. Three groups of approximately equal size were then formed based on initial prostate volumes: Group A (N=75): 0-25cc; Group B (N=76): 26-40cc; and Group C (N=67):>40cc.
Results: The mean age was 54.2 yrs. Transdermal gel was used by 70% of men, and almost all the rest received intramuscular testosterone injections. No significant differences at baseline were noted between groups with regard to age, TT, FT, or mode of therapy. Testosterone treatment resulted overall in a PSA increase from 1.36 to 1.57 ng/ml (p<0.0001). A significant PSA increase was noted only for younger men, in Groups 1 and 2, but not for older men, in Groups 3 and 4 (p<0.05). Baseline PSA correlated with prostate volume at baseline. Testosterone treatment resulted in a PSA increase of 29% for Group A (1.05 to 1.35 ng/ml, p<0.0001), 18% for Group B (1.22 to 1.44 ng/ml, p<0.0001), and 10% for Group C (2.21 to 2.42 ng/ml, p=0.167).
Conclusions: The rise in PSA following TRT is influenced by age and prostate size. A significant rise in PSA was noted in younger men, but not in men older than 60 years. In addition, the greatest proportional PSA increase was seen in men with smaller prostate volumes. No significant increase was seen for men with prostate volume greater than 40 cc.