Topically applied testosterone and phallic growth. Its effects in male children with hypopituitarism and microphallus

Topical application of 5% testosterone cream for 21 days resulted in enlargement of the penis to normal size for age in five boys with normal XY karyotype who had microphallus and hypopituitarism. In four patients, testosterone cream was applied locally to the penis and in one to an area of skin in the right axilla. Serum testosterone values rose from infantile levels before the start of therapy to normal adult male levels on the last day of treatment. All patients were receiving human growth hormone at the time of therapy with testosterone. No additional acceleration of linear growth and no advance in osseous maturation occurred during or after treatment. Application of testosterone locally for this brief period is a safe, effective, and simple means of stimulating phallic growth. Our findings suggest that topical testosterone causes penile growth predominantly through its systemic action.