Exploring the efficacy of testosterone undecanoate in male children with 5α‐reductase deficiency

IMPORTANCE: Children with 5‐alpha‐reductase deficiency (5α‐RD) and hypospadias present with micropenis, which makes it difficult to obtain sufficient tissue for urethral reconstruction. OBJECTIVE: We investigated the therapeutic effects of oral testosterone undecanoate and established a standard androgen treatment protocol for patients with 5α‐RD with micropenis. METHODS: Patients with 5α‐RD were treated with oral testosterone undecanoate for 3 months as a course. All patients were treated with no more than 3 courses. If the penile length (PL) reached 2.5 cm (the minimum criterion for surgery) or greater than or equal to −2.5 standard deviations (SDs) (lower limit of normal), testosterone undecanoate was considered to be effective. RESULTS: The median age of 90 patients with 5α‐RD was 1.7 years (0.9, 3.1 years). The baseline PL was 1.9 ± 0.6 cm before treatment. At the end of the first course, the PL of 63 patients (70%) reached 2.5 cm, and 49 patients (54%) reached greater than or equal to −2.5 SDs. After two treatment courses, the PL of 81 patients (90%) reached 2.5 cm, and 90 patients (100%) reached greater than or equal to −2.5 SDs. After three courses, the PL of all patients reached 2.5 cm, and all patients reached a PL greater than or equal to −2.5 SDs. No abnormal increase was observed in height‐SD score, weight‐SD score, or ratio of bone age to chronological age during the 1–3‐year follow‐up. INTERPRETATION: After 3–9 months of treatment, PL increased to the target length. No severe adverse reactions were observed during follow‐up. Testosterone undecanoate was safe and effective in children with 5α‐RD with micropenis.