Efficacy and safety of percutaneous administration of dihydrotestosterone in children of different genetic backgrounds with micropenis.

BACKGROUND

Exogenous androgen supplement is an optional treatment for micropenis; however, its use in childhood is controversial due to potential side effects.

METHODS

Twenty-three children (mean age: 4.07±3.4 years) with micropenis of unknown causes harboring the 46,XY karyotype were recruited in an open prospective study. Androgen receptor (AR), steroid 5α-reductase-2 (SRD5A2), and SRY genes were sequenced; 2.5% dihydrotestosterone (DHT) transdermal gel (0.1-0.3 mg/kg/day) was applied and titrated within the normal DHT serum reference ranges. Stretched penile length (SPL) was measured before therapy, and after 1, 3 and 6 months of DHT gel treatment, respectively.

RESULTS

Two patients were found with AR gene mutations and five patients with SRD5A2 gene mutations. Average stretched penile lengths (SPLs) were 1.68±0.6 cm at baseline and 2.2±0.66 cm, 2.6±0.59 cm and 2.9±0.55 cm (mean ± 1 SD) after 1, 3 and 6 months of treatment, respectively. Fourteen cases (61%) reached standard penile length ranges (>-2.5 SD) and medication was discontinued; six cases (26%) were satisfied with the improved penile lengths despite failing to reach the aged matched standards. Three infants (13%) discontinued the medication after 3 months due to anxiety about the potential side effects. No significant side effects were found except the elevated DHT serum levels after therapy.

CONCLUSIONS

Short term and local application of DHT at low doses in patients with micropenis could accelerate penile growth effectively without evident side effects; however, precautions still need be taken due to the paucity of long term study and the lack of ideal DHT dosage.