Endocrine Abstracts

Introduction: The pathogenesis of short stature and growth failure in Turner syndrome (TS) is multifactorial, and includes low birthweight, ovarian failure and skeletal dysplasia. Although abnormalities of the GH-IGF1 axis are implicated, patients are not GH-deficient (GHD) and consequently non-GHD doses of GH are utilised ie. 45–50 μg/kg per day or 9.8 mg/m² per week. Although initially used in GHD patients, IGF1 titration is increasingly being used in all GH-treated patients, with little evidence base.

Methods: Girls with TS attending a tertiary growth centre have been retrospectively reviewed. Girls were included if they had been IGF-1 titrated, received GH for at least a year and were more than a year from stopping GH.

Results: A total of 20 girls were identified, median age 12.8 years (range 7.1–16.2). Ten had a 45X karyotype; 7 were TS mosaic and the remainder TS variants. The mean(S.D.) GH dose was 25.6(7) mg/kg per day or 5.9(1.8) mg/m² per week; none were receiving the currently recommended dose of GH. Twelve girls were also receiving oxandrolone, 10 oestrogen, including 8 who were receiving both. The mean(S.D.) height velocity was 5.32(1.48) cm/years or 2.12(1.9)SDS. IGF1 levels performed at the same time were within the normal range in 11 (but high normal in 2), and raised in 9. Four girls (2 with 45X karyotype) have achieved final height; all have a height >150 cm (range 150.4–156.3) with a final height SDS for TS ranging from +1.6 to +2.7.

Conclusions: IGF1 titration in girls with TS results in much lower GH doses than those recommended within the GH license. Whilst growth is maintained and limited data indicates an acceptable final height, further work is required to assess whether this is equivalent to that achieved with standard doses of GH, and also whether IGF1 levels are raised at the onset of GH therapy, indicating IGF1 resistance.