Growth hormone therapy in Turner's syndrome. Impact of injection frequency and initial bone age.

STUDY OBJECTIVE

To determine the influence of the injection frequency and the initial bone age on the efficacy of treatment with biosynthetic growth hormone in Turner's syndrome.

DESIGN

Randomized study.

SETTING

Referral-based pediatric endocrinology departments of seven university medical centers.

PATIENTS

Fifty-two patients with Turner's syndrome confirmed with chromosomal analysis.

TREATMENT

Somatotropin recombinant DNA (24 IU/m2 of body surface area) subcutaneously administered in three or six injections per week for 2 years. Patients who were older than 12 years at the beginning of the study received low doses of estrogen.

RESULTS

The following statistically significant findings supported the use of six injections per week compared with three injections per week: the mean (+/- SD) increment in height during 2 years was 11.3 cm (3.8 cm) with six injections vs 8.6 cm (3.4 cm) with three injections; the increment in height standard deviation score was 0.9 cm (0.5 cm) vs 0.6 cm (0.3 cm); the growth velocity was 6.6 cm/y (2.0 cm/y) vs 5.2 cm/y (1.7 cm/y) in year 1 and 4.7 cm/y (2.0 cm/y) vs 3.4 cm/y (1.7 cm/y) in year 2; and the increment in height standard deviation score for bone age was 0.8 cm (0.5 cm) vs 0.4 cm (0.6 cm). For patients whose initial bone age was more than 13 years, growth velocity increased by 1 to 2 cm in year 1; in year 2 no increment was observed. We did not observe adverse effects.

CONCLUSIONS

Biosynthetic growth hormone in a higher-frequency regimen in Turner's syndrome is more efficient in terms of increment in height, growth velocity, and height standard deviation score for bone age than treatment in a lower-frequency regimen. In patients with an initial bone age of more than 13 years, the response was poor. Longer follow-up is necessary to assess the effect on final height.