Final Height in Girls with Turner Syndrome after Long-Term Growth Hormone Treatment in Three Dosages and Low Dose Estrogens

Abstract

Although GH treatment for short stature in Turner syndrome is an accepted treatment in many countries, which GH dosage to use and which age to start puberty induction are issues of debate. This study shows final height (FH) in 60 girls with Turner syndrome treated in a randomized dose-response trial, combining GH treatment with low dose estrogens at a relatively young age. Girls were randomly assigned to group A (4 IU/m2·d; ∼0.045 mg/kg/d), group B (first year, 4 IU/m2·d; thereafter 6 IU/m2·d), or group C (first year, 4 IU/m2·d; second year, 6 IU/m2·d; thereafter, 8 IU/m2·d). After a minimum of 4 yr of GH treatment, at a mean age of 12.7 ± 0.7 yr, low dose micronized 17β-estradiol was given orally. After a mean duration of GH treatment of 8.6 ± 1.9 yr, FH was reached at a mean age of 15.8 ± 0.9 yr. FH, expressed in centimeters or sd score, was 157.6 ± 6.5 or −1.6 ± 1.0 in group A, 162.9 ± 6.1 or −0.7 ± 1.0 in group B, and 163.6 ± 6.0 or −0.6 ± 1.0 in group C. The difference in FH in centimeters, corrected for height sd score and age at start of treatment, was significant between groups A and B [regression coefficient, 4.1; 95% confidence interval (CI), 1.4, 6.9; P < 0.01], and groups A and C (coefficient, 5.0; 95% CI, 2.3, 7.7; P < 0.001), but not between groups B and C (coefficient, 0.9; 95% CI, −1.8, 3.6). Fifty of the 60 girls (83%) had reached a normal FH (FH sd score, more than −2). After starting estrogen treatment, the decrease in height velocity (HV) changed significantly to a stable HV, without affecting bone maturation (change in bone age/change in chronological age). The following variables contributed significantly to predicting FH sd score: GH dose, height sd score (ref. normal girls), chronological age at start of treatment, and HV in the first year of GH treatment. GH treatment was well tolerated. In conclusion, GH treatment leads to a normalization of FH in most girls, even when puberty is induced at a normal pubertal age. The optimal GH dosage depends on height and age at the start of treatment and first year HV.