Wednesday, July 24, 2013

Effects of Testosterone on Boys with Micropenis

In this article we'll examine a study published in the late 90s named "Congenital hypogonadotropic hypogonadism and micropenis: effect of testosterone treatment on adult penile size and why sex reversal is not indicated."

Purpose of the study was to assess the safety and efficacy of testosterone treatment in young patients presenting with the micropenis condition.

Patient Background
A total of 8 patients - all with micropenis secondary to congenital pituitary gonadotropin deficiency - participated in the study. The patients were followed from their infancy or early childhood to adulthood (from 18 to 27 years of age) and were divided into two groups:
  • Four boys that received testosterone treatment before reaching the age of 2. Their mean stretched penile length, prior to treatment, was 1.1 cm (min: 0.5, max: 1.5 cm ).
  • Four boys that received testosterone treatment between the ages of 6 to 13. Their mean stretched penile length, prior to treatment,  was 2.7 cm (min:1.5 cm, max: 3.5 cm)
Image showing a newborn boy with the micropenis condition
Infant with micropenis
More micropenis photos

Treatment method
Both groups received one or more courses of 3 intramuscular injections containing testosterone enanthate (25 or 50 mg) at 1-month intervals. After the onset of puberty, the dosage was gradually increased to 200 mg on a monthly basis and then to an adult replacement regimen.

The authors reported similar penile gains for all boys, with both groups attaining - in adulthood - a penis with an average stretched length of 10.3 cm (min: 8 cm, max: 14 cm). Taking into consideration that the mean adult stretched penile length for Caucasians is 12.4, the results were described as quite satisfactory.

The researchers also reported that six of the patients "were sexually active, and all reported normal male gender identity and psychosocial behavior."

The study's main conclusions are as following:
  • One or two short courses of testosterone therapy are effective in enlarging a micropenis resulting from testosterone deficiency
  • There is no reason - clinical, psychological or physiological - to have a boy with micropenis sexually reassigned to a girl
  • The study contradicts previous clinical data on testosterone therapy - derived from mouse models - which indicated that early testosterone treatment may impair penile growth in adolescence and compromise adult penile length.
testosterone therapy is a viable option for children with micropenis

What if it doesn't work?
If testosterone therapy fails then there is still hope.For example, transdermal Dihydrotestosterone application has shown some promising results in such patients.

Bin-Abbas B, Conte FA, Grumbach MM, & Kaplan SL. (1999) Congenital hypogonadotropic hypogonadism and micropenis: effect of testosterone treatment on adult penile size why sex reversal is not indicated. The Journal of pediatrics, 134(5), 579-83. PMID: 10228293


  1. Can adults with micropenises gain any type of a positive result from this treatment?

    1. No. After puberty phallus size can no longer be altered by hormonal management.


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