Micropenis: does early treatment with testosterone do more harm than good?

Micropenis secondary to hypogonadotropic hypogonadism was induced in the Sprague-Dawley rat using long acting microspheres of the gonadotropic agonist leuprolide acetate. Following the induction of micropenis treatment was initiated with testosterone at day 7, 28, 56 or 84 of life. All treatment protocols resulted in improved phallic growth compared to the untreated animals with micropenis (p < 0.01). Treatment of animals with testosterone beginning on day 7 of life resulted in premature growth of the penis and the redevelopment of micropenis in adulthood. In contrast, delaying testosterone therapy until day 56 (pubertal) or 84 (early postpubertal) resulted in complete penile development. These findings suggest that early exposure of the penis to androgens in childhood may eventually result in a significant reduction of phallic size in adulthood.