Growth hormone therapy in Turner syndrome--current uncertainties and future strategies.

The effect of growth hormone (GH) on short-to-medium-term growth in girls with Turner syndrome is well-established. However, it is only relatively recently that final height data have become available. This paper reviews 10 reports from Europe (including Sweden, Austria, France, Holland, Belgium and Scotland), Canada, USA and Japan, on final height and near-final height in girls with Turner syndrome receiving GH therapy. An improvement in final height outcome versus projected adult height was found in all the studies, except for the Scottish study, in which the median final height was only 142.6 cm, and the Canadian study, in which the projected adult height was unexpectedly high at 148.2 cm. Although the mean final height was 150 cm or greater in six studies, all 10 showed considerable individual variation in final height with minimum values ranging between 131.5 and 145 cm. These results must be interpreted cautiously since the mean age of starting treatment was relatively late at 9.1-13.1 years. However, the overall modesty and interpatient variability of response to GH in Turner syndrome, and continuing uncertainty as to the role of oxandrolone and the timing of estrogen therapy, emphasizes the need for further research. National and international collaboration in both retrospective and prospective studies are necessary to achieve sufficient data to offset the large number of variables to be analysed. In the UK, the British Society for Paediatric Endocrinology and Diabetes hopes to do a retrospective meta-analysis of final/near-final height outcome, comparing this with midparental and maternal height, as well as projected height and control data. A prospective study with GH dose standardized at 30 IU/m2 per week in the form of daily injections, with randomization to receive oxandrolone or not at 9 years, and estrogen at either 12 or 14 years, is also planned.