Growth Hormone plus Childhood Low-Dose Estrogen in Turner's Syndrome

BACKGROUND Short stature and ovarian failure are characteristic features of Turner's syndrome. Although recombinant human growth hormone is commonly used to treat the short stature associated with this syndrome, a randomized, placebo-controlled trial is needed to document whether such treatment increases adult height. Furthermore, it is not known whether childhood estrogen replacement combined with growth hormone therapy provides additional benefit. We examined the independent and combined effects of growth hormone and early, ultra-low-dose estrogen on adult height in girls with Turner's syndrome. METHODS In this double-blind, placebo-controlled trial, we randomly assigned 149 girls, 5.0 to 12.5 years of age, to four groups: double placebo (placebo injection plus childhood oral placebo, 39 patients), estrogen alone (placebo injection plus childhood oral low-dose estrogen, 40), growth hormone alone (growth hormone injection plus childhood oral placebo, 35), and growth hormone-estrogen (growth hormone injection plus childhood oral low-dose estrogen, 35). The dose of growth hormone was 0.1 mg per kilogram of body weight three times per week. The doses of ethinyl estradiol (or placebo) were adjusted for chronologic age and pubertal status. At the first visit after the age of 12.0 years, patients in all treatment groups received escalating doses of ethinyl estradiol. Growth hormone injections were terminated when adult height was reached. RESULTS The mean standard-deviation scores for adult height, attained at an average age of 17.0 +/- 1.0 years, after an average study period of 7.2 +/- 2.5 years were -2.81 +/- 0.85, -3.39 +/- 0.74, -2.29 +/- 1.10, and -2.10 +/- 1.02 for the double-placebo, estrogen-alone, growth hormone-alone, and growth hormone-estrogen groups, respectively (P<0.001). The overall effect of growth hormone treatment (vs. placebo) on adult height was a 0.78 +/- 0.13 increase in the height standard-deviation score (5.0 cm) (P<0.001); adult height was greater in the growth hormone-estrogen group than in the growth hormone-alone group, by 0.32 +/- 0.17 standard-deviation score (2.1 cm) (P = 0.059), suggesting a modest synergy between childhood low-dose ethinyl estradiol and growth hormone. CONCLUSIONS Our study shows that growth hormone treatment increases adult height in patients with Turner's syndrome. In addition, the data suggest that combining childhood ultra-low-dose estrogen with growth hormone may improve growth and provide other potential benefits associated with early initiation of estrogen replacement.