AGE AS A DETERMINANT OF THE IMPACT OF GROWTH-HORMONE THERAPY ON PREDICTED ADULT HEIGHT

OBJECTIVE Final adult height is determined by both childhood and puber tal growth. The: later is a function of growth velocity and bone matur ation, and both are regulated by growth hormone. In a study of the saf ety and efficacy of GH therapy, we analysed the impact of age on bone maturation and predicted adult height. PATIENTS AND METHODS The subjec ts were 65 male patients with GH deficiency, as diagnosed by pharmacol ogical or physiological tests, who participated in a multicentre trial and completed 3 years of hGH therapy. The age range at initiation of therapy was 3.1-5.7 years. Subcutaneous injections of hGH were given i n a dose of 0.3 mg/kg/week, in thrice-weekly doses. Calculation of the adult height prediction was performed on annual growth parameters usi ng the Bailey-Pinneau, TW-II and Roche methods. RESULTS The rate of pu bertal advancement correlated positively with the child's age at initi ation of therapy. The bone age advanced in positive correlation with c hronological age, and by the end of 3 years of hGH therapy the delta-b one age/delta-chronological age ratio increased to 1.5 for children wi th an age at start of therapy of 10.7 years. During the adolescent yea rs, the predicted gained height over 3 years of therapy declined, in:c orrelation with age, and became negative at a therapy-initiation age o f 12.9 years. CONCLUSIONS In a retrospective analysis of a group of ch ildren with heterogeneous GH secretory ability, GH induced acceleratio n of growth, around the age of normal puberty, advanced the age of pub ertal onset and accelerated pubertal progression which, in turn, exped ited bone maturation and thereby restricted predicted adult height gai n from hGH therapy.