Clinical Predictors of Response to Testosterone Replacement Therapy in Boys With Micropenis: A Retrospective Study Focusing on Penile Morphology and Hormonal Factors.

Baseline pretreatment stretched penile length and glans width were identified as independent predictors of testosterone replacement therapy response in boys with micropenis.

• Logistic regression analysis was used to identify predictors of favorable response.
• Glans width showed stronger predictive power than stretched penile length.
• The study included 37 boys aged ≤3 years with micropenis treated at Nagasaki University Hospital between April 2019 and March 2024.
• Treatment consisted of three intramuscular injections of testosterone enanthate (25 mg at monthly intervals).

There were statistically significant differences in stretched penile length and glans width among the three response groups (good, intermediate, and poor).

• Patients were classified into three response groups based on post-treatment stretched penile length standard deviation scores: good (Group 1), intermediate (Group 2), and poor (Group 3).
• Baseline pre-treatment stretched penile length, glans width, hormone levels, and timing of testosterone replacement therapy were compared among groups.
• The differences in stretched penile length and glans width among groups were described as statistically significant.

Testosterone replacement therapy initiated during mini-puberty was more frequent in the poor response group (Group 3) than in the other groups, though this difference was not substantial.

• Treatment timing relative to the mini-puberty period was analyzed as a potential predictor.
• The higher frequency of mini-puberty-period treatment initiation in Group 3 did not reach a level considered substantial by the authors.
• This finding suggests treatment timing during mini-puberty may not be a strong independent predictor of response.

Initial penile dimensions, particularly glans width, were identified as reliable predictors of testosterone replacement therapy efficacy in boys with micropenis.

• Glans width demonstrated stronger predictive power than stretched penile length in logistic regression analysis.
• The study is retrospective in design, including 37 boys aged ≤3 years.
• The authors note that further prospective studies are warranted to optimize treatment timing and assess underlying hormonal and genetic factors.

The study population consisted of 37 boys aged ≤3 years with micropenis who received a standardized testosterone enanthate regimen.

• Treatment was three intramuscular injections of testosterone enanthate at 25 mg at monthly intervals.
• Patients were treated at Nagasaki University Hospital between April 2019 and March 2024.
• Baseline measures included stretched penile length, glans width, hormone levels, and treatment timing relative to mini-puberty.