Growth hormone (GH) secretion and response to GH therapy after total body irradiation and haematopoietic stem cell transplantation during childhood.

Objective: In January 1997 we introduced a protocol for the treatment with GH of children with impaired growth after unfractionated total body irradiation (TBI). This study is an evaluation of that protocol.
Patients and Methods: Between January 1997 and July 2005, 66 patients (48 male) treated for haematological malignancies had at least two years of disease-free survival after TBI-based conditioning for stem cell transplantation (SCT). Stimulated and/or spontaneous GH secretion was decreased in 8 of the 29 patients tested because of impaired growth. Treatment with GH (daily dose 1.3 mg/m2 body surface area) was offered to all 29 patients and initiated in 23 of them (17 male). The main outcome measure was the effect of GH therapy on height standard deviation scores (SDS) after onset of GH therapy, estimated by random-effect modelling with corrections for sex, age at time of SCT and puberty (data analysed on intention-to-treat basis).
Results: At time of analysis, median duration of therapy was 3.2 years; median follow-up after start of GH therapy was 4.2 years. The estimated effect of GH therapy, modelled as nonlinear (logit) curve, was +1.1 SD after 5 years. Response to GH therapy did not correlate to GH secretion status.
Conclusion: GH therapy has a positive effect on height SDS after TBI, irrespective of GH secretion status.