Mauras N et al. (2008) Anastrozole increases predicted adult height of short adolescent males treated with growth hormone: a randomized, placebo-controlled, multicenter trial for one to three years. J Clin Endocrinol Metab 93: 823–831

Estrogen is a principal regulator of epiphyseal fusion in females and males. Mauras et al. conducted a double-blind, randomized, placebo-controlled trial to determine whether estrogen suppression with the selective aromatase inhibitor anastrozole, administered to growth hormone (GH)-deficient adolescent boys who were also receiving GH therapy, delays epiphyseal fusion (and, therefore, retards bone-age advancement) and whether it increases predicted adult height.

Patients were randomly allocated to receive anastrozole 1 mg daily or placebo, in addition to their usual GH therapy, and were examined at 3-month intervals. Anastrozole treatment continued for 36 months or until completion of linear growth. Of the 52 patients recruited, 50, 41 and 28 completed 12 months, 24 months and 36 months of treatment, respectively.

Bone-age advancement was slower in anastrozole-treated boys, compared with placebo-treated boys. Differences in bone age between the groups were significant after 24 months and 36 months of treatment. Predicted adult height gain from baseline was greater in anastrozole-treated than placebo-treated boys, with an increase of 4.5 ± 1.2 cm after 24 months and 6.7 ± 1.4 cm after 36 months in the anastrozole arm, compared with a gain of 1 cm at both time points in the placebo arm. Pubertal progression rates were similar in both groups.

The authors conclude that 2–3 years of anastrozole treatment is effective in GH-deficient adolescent boys on GH therapy. Long-term follow-up will be needed to fully evaluate the safety and efficacy of this treatment.