Although growth hormone therapy has been available for more than 10 years, there are few data regarding its long-term effect on height or timing of onset of puberty in girls. A major concern is that any gain in prepubertal height could be lost in puberty if growth hormone therapy interferes with the size or duration of the pubertal growth spurt. McCaughey and colleagues conducted a randomized controlled trial to study the effect of growth hormone therapy on final height and pubertal development in girls.
The authors identified 40 girls who were at least two standard deviations below the mean height for their age and had no medical condition to account for their short stature. The parents of 18 girls consented to have their daughters participate in the study. The mean age of the girls at the start of the study was 8.07 years. Ten of these girls received 30 U of somatropin every week, given in daily subcutaneous injections. The remaining eight girls were assigned to a control group and received no treatment.
All 18 girls were intensively monitored. Height (both standing and sitting) and weight of study participants were measured every six months to assess body proportions. Bone age assessments, serum biochemical profiles, serum insulin and insulin-like growth factor 1 were measured annually. The 22 girls who declined to enter the study were monitored for standing height and weight every six months. Treatment lasted until the girls reached menarche and had at least stage 4 breast development (mean: 6.2 years).
The three groups had similar growth patterns at baseline; girls in the nonconsent group were slightly taller than girls in the other groups. During the trial, the girls receiving treatment grew significantly more than the girls in the two nontreatment groups. By 16 years of age, girls who received treatment were taller than those in the non-treatment group by 7.5 cm and were 6.0 cm taller than those who declined to participate in the study. All of the girls in the treatment group reached their target heights, compared with 38 percent of the girls who did not receive treatment. This difference was statistically significant. Age at menarche and other measures of puberty and development did not differ significantly between the groups.
The authors conclude that growth hormone therapy promotes height gain without compromising the process of puberty or its associated growth spurt. In considering the benefits of this therapy, the authors raise ethical and financial issues. Height gain and possible psychosocial benefits have to be balanced against cost. No significant psychosocial benefits have yet been shown. The authors estimate that each centimeter of height gained with the use of growth hormone therapy costs approximately $18,000.