Final height in young women with Turner syndrome after GH therapy: an open controlled study

Abstract

GH therapy has been applied to patients with Turner syndrome for over a decade, but small sample size, delayed initiation of therapy into adolescent age and comparison with historical control subjects limit the usefulness of these studies for appraisal of the effect of GH on final adult height. We report 49 young women with Turner syndrome who completed a clinical trial in an open, non-randomized, age-matched controlled study of GH, given as daily s.c. injections at a weekly dose of 8.2 mg/m(2) for 1.9-7.5 years. Final height was defined as the measurement taken 2 years or more after height velocity declined below 2 cm/year and after a bone age of 15 'years'. The gain in height was evaluated in three ways. The mean final height gain, compared with the control group, was 4.4 cm. When corrected for the projected height at inception of therapy, the mean gained height was 5.3 cm above the control group. Shorter girls showed better response to GH then did taller girls. After correcting for parental height, the mean gain was 4.7 cm. The adult height of the GH-treated Turner women was significantly correlated with the target height, whereas no such correlation was obtained for control untreated women. Furthermore, no correlation was observed between height gain and the age or duration of GH therapy, or the age of inception of estrogen replacement therapy. It is concluded that GH therapy augments final height of girls with Turner syndrome by a mean 4.4-5.3 cm, depending on the method of evaluation, and that shorter girls may be preferred candidates for such therapy. GH therapy can be initiated after age 10 years and there is no reason to delay estrogen therapy beyond the age of 12. Indirect evidence suggests that high-dose GH therapy may surmount a pathophysiological resistance in the GH-IGF-I axis.