Growth hormone substitution in adult growth hormone-deficient men augments androgen effects on the skin.

OBJECTIVE

To assess whether growth hormone (GH) administration to adult GH-deficient men leads to increased sexual hair. The sexual hair scores are subnormal in these patients, even in the presence of normal serum androgen levels.

PATIENTS

Forty-six adult men with childhood-onset of GH deficiency of whom 25 were androgen deficient and received replacement.

DESIGN

Double-blind and placebo-controlled. Of the 46 patients, 33 started immediately with GH administration; the remaining 13 received placebo for the first 6 months followed by GH for the next 6 months. Sixty-one age-matched healthy men with normal height and serum concentrations of IGF-I served as a comparison group.

MEASUREMENTS

Hair scores at 13 defined body regions were assessed before, and after 6 and 12 months of the intervention. At the same time levels of IGF-I, dehydroepiandrosterone sulphate, androstenedione, dihydrotestosterone (DHT), testosterone and sex hormone binding globulin (SHBG) were measured. From the latter two, the free androgen index (FAI) was calculated.

RESULTS

Before GH administration, hair scores in the GH deficient patients were lower than in the comparison group. In the 33 men treated with GH from the beginning, there was an increase in hair scores after 6 months. The increase in hair scores was not seen during 6 months of placebo treatment. When the placebo group switched to GH administration, their hair scores had also significantly increased after 6 months of GH substitution therapy. Upon GH administration both levels of SHBG and testosterone/DHT declined while the FAI remained unchanged.

CONCLUSION

GH substitution therapy to GH deficient men has an auxiliary effect on androgen action in the skin without an increase of the FAI.