487 THE EFFECT OF LOW DOSE ESTRADIOL ON 6 MONTH GROWTH RATES IN PATIENTS WITH TURNER'S SYNDROME

Abstract

We previously noted a biphasic dose-response curve for ethinyl estradiol (EE2) on short term growth in girls with Turner's syndrome. Optimal growth occurred at the dose of 100 ng/kg/d (4 ug/d in a 40 kg girl). In the current study we asked whether the growth stimulation at the dose of 100 ng/kg/d would be sustained during a 6 month period and whether bone age advancement would be accelerated. We randomly assigned 16 girls with Turner's syndrome, age 5 to 15 y, to treatment with 100 ng/kg/d EE2 or placebo for 6 months, after observing basal growth for 2 months. We assessed growth by the 4-week lower leg growth rate (LLGR), and by height measurements, and we determined bone age at the beginning and end of treatment. The results are shown below. Low dose EE2 stimulated growth over a six month period without advancing bone age relative to placebo. Breast development advanced one Tanner stage in 2 of the 8 EE2 treated patients. Serum somatomedin C concentrations did not change significantly during treatment. We conclude that ethinyl estradiol at the dose of 100 ng/kg/d for 6 months produces sustained growth without bone age acceleration in girls with Turner's syndrome.