Intervention: At entry subjects are already receiving GH treatment according to general clinical practice, and are expected to demonstrate an IGF-I concentration of 0 - 1 SD score (SDS) (normal dose). The group of men and group of women will be randomized to receive either a decrease of their regular dose of GH treatment (IGF-I target level of -2 - -1 SDS) (low dose), or an increase of their regular dose, (IGF-I target level of 1 - 2 SDS) (high dose) for at least 24 weeks.