Objectives. This study examined the effects of testosterone replacement using a nonscrotal testosterone transdermal (TTD) system on prostate size and prostate-specific antigen (PSA) levels in hypogonadal men. Methods. As part of an open-label, multicenter study, prostate volume as measured by transrectal ultrasound and PSA were assessed in 29 hypogonadal men during treatment with intramuscular testosterone enanthate (+TE), followed by 8 weeks of androgen withdrawal (-T), and then during 1 year of therapy with Androderm Testosterone Transdermal System, a nonscrotal permeation-enhanced TTD system (+TTD). Results. Mean prostate volume decreased significantly from the +TE period (17 g) compared with the T period (14 g) (P <0.001). Prostate volume increased significantly from the -T period compared with the +TTD period (18 g) (P <0.001). Maximum prostate size, comparable to that measured during +TE (P = 0.125), was reached by month 3 of +TTD therapy; prostate volume did not increase further during the remaining 9 months of +TTD therapy. Prostate volume correlated with age (P <0.01) during all three periods of observation (+TE: r = 0.69; T: r = 0.64; and +TTD: r = 0.55). No patient developed symptomatic benign prostatic hyperplasia during the treatment period. PSA levels decreased during androgen withdrawal compared with levels measured during +TE treatment (P <0.001) and rose with resumption of androgen therapy with TTD (P <0.006). However, PSA levels during +TTD replacement remained significantly lower (P <0.001) than during +TE replacement. Conclusions. Physiologic testosterone replacement in hypogonadal men was achieved using the TTD system. Prostate size during therapy with TTD was comparable to that reported for normal men. In these men treated with TTD, PSA levels were also within the normal range.
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