TLDR Dihydrotestosterone treatment can help penis growth in boys with 5α-reductase deficiency but doesn't fully normalize size after puberty.
In a study from 2019, four Japanese boys with micropenis due to 5α-reductase type 2 deficiency (5αRD2) were treated with dihydrotestosterone (DHT). The boys, aged 4-11, experienced an increase in stretched penile lengths (SPLs) from a median of 2.6 cm to 4.4 cm after prepubertal DHT treatment. However, post-pubertal penile growth was limited despite normal testosterone levels, and a second course of DHT treatment during ages 12-18 did not normalize SPLs, which ranged from 6.0 to 7.0 cm. Two patients had variable prostate volumes, and one had a normal sperm count as a young adult. The study concluded that while DHT treatment aids in penis and prostate development, potentially supporting fertility, it also presents challenges in managing post-pubertal growth and the risk of prostate overgrowth in males with 5αRD2.
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