Impact of Growth Hormone Supplementation on Adult Height in Turner Syndrome: Results of the Canadian Randomized Controlled Trial

Abstract

A randomized, controlled trial of GH supplementation to adult height in girls with short stature due to Turner syndrome was conducted in Canada. We report results in subjects who completed the protocol and subjects who participated in follow-up. One hundred fifty-four girls with Turner syndrome, aged 7-13 yr, were randomly assigned to one of two groups: 1) GH by sc injection six times per week (0.30 mg/kg.wk), and 2) control (C), no GH treatment. Both cohorts received standardized sex steroid replacement starting at a chronological age of 13 yr. Subjects were followed until protocol completion, defined as height velocity less than 2 cm/yr and bone age 14 yr or greater. A subsequent protocol addendum requested follow-up safety and efficacy assessment in all patients at least 1 yr after the last core protocol visit. One hundred four patients completed the study (61 GH, 43 C), and 50 withdrew (15 GH, 35 C). At protocol completion, mean heights were 147.5 +/- 6.1 (GH) and 141.0 +/- 5.4 cm (C), respectively (P < 0.001). Of those who completed the protocol, 59 (40 GH, 19 C) had height data at least 1 yr after protocol completion; in that group, mean heights were 149.0 +/- 6.4 (GH) and 142.2 +/- 6.6 cm (C), respectively (P < 0.001). At protocol completion and follow-up, the mean height gain due to GH, estimated by analysis of covariance, was +7.2 cm (confidence interval 6.0, 8.4) and +7.3 cm (confidence interval 5.4, 9.2), respectively (both P < 0.001). This is the first evidence from a randomized, controlled trial to adult height that GH supplementation with induction of puberty at a near physiological age increases the adult height of girls with Turner syndrome.