The effect of different growth hormone administration frequencies on growth in growth hormone-deficient patients

In two different groups of clinically prepubertal children (bone age less than or equal to 8 years) with isolated growth hormone deficit we have evaluated either if the substitutive therapy administered by pump (permitting between 20.00 and 08.00 h the association of continuous and intermittent subcutaneous growth hormone administration) could improve growth (study A) or if a 3 times/week schedule treatment could be performed without any negative effect on growth with respect to 6 injections/week (study B). All patients had been previously successfully treated for at least 2 years by the same dose used during both studies (0.6 IU/kg/week) administered at bedtime 6 times/week. Study A: Each child underwent at bedtime both pump administration (6 months) and single daily injection (6 months). The circulating IGF-I pattern as well as the growth velocity and the ratio bone age increase/height age increase did not differ during the two treatment regimens. Study B: No differences were observed in auxological parameters during the treatment schedule on 3 times/week compared to the previous year on 6 times/week. In conclusion: Our treatment, consisting of the association of continuous and intermittent subcutaneous growth hormone administration, did not improve growth velocity with respect to single daily subcutaneous injection; the growth hormone administration 3 times/week, starting at the 3rd year of substitutive therapy or later, seems to have no negative effect on growth with respect to 6 injections/week.