Dutasteride in men receiving testosterone therapy: a randomised,double‐blind study

We investigate the impact of dutasteride on prostate specific antigen (PSA) and prostate volume in men receiving testosterone (T) therapy. Twenty‐three men on stable dose T therapy were randomised to receive either dutasteride or placebo for 12 months. Serum levels of PSA, T and dihydrotestosterone (DHT) and responses to the International Index of Erectile Function (IIEF) and Male Sexual Health Questionnaire (MSHQ) questionnaires were determined at baseline and at 3, 6, 9 and 12 months. Prostate volume (PV) was measured using transrectal ultrasound (TRUS) at baseline and again after 12 months. A total of 22 men (mean age 57.3) completed the study, with 11 men receiving placebo and 11 receiving dutasteride. Men receiving dutasteride had a significant decrease in PSA (?0.46 ± 0.81 ng ml^?1; P = 0.04) and in PV (?6.65 ± 11.0%; P = 0.03) from baseline over 12 months. DHT decreased significantly for men on dutasteride compared with men receiving placebo (P = 0.02). When compared with men who received placebo, men who received dutasteride demonstrated nonsignificant trends towards decreased PSA (?0.46 versus 0.21 ng ml^?1; P = 0.11), PV (?6.65% versus 3.4%; P = 0.08) and MSHQ scores (?10.2 versus 5.6; P = 0.06). Dutasteride reduces PSA and PV for men on T therapy, but perhaps less so than in men without T therapy.