ESPE Abstracts

Background: GnRHa therapy is shown to be beneficial in increasing final height when started before 6 years of age in girls with idiopathic CPP(iCPP). However controversial data exist in improvement of final height whose pubertal signs appear after age of 6.

Aim: To investigate effect of age of onset of GnRHa therapy on final height n girls with iCPP, and to evaluate factors affecting height gain.

Methods: Eighty-four girls with iCPP who were treated with GnRHa and had reached final height were included.These cases were grouped as <6yrs, 6-6.9yrs, 7-7.9yrs, ≥8yrs according to age of initiation of therapy.Final heights of these cases were compared with data of 18 girls with CPP who refused therapy.Height gain was defined as difference between final height and predicted adult height(PAH) at start of therapy.Rate of bone age maturation was calculated by dividing difference between bone ages at the end and beginning of therapy by duration of therapy.

Results: There was no significant difference in terms of height gain between patients who started GnRHa therapy after 8 years of age and those who were not treated(5.9±4.2cmvs5.7±4.0cm)(p:0.852). Height gain of those who started GnRHa before age of 8 was significantly higher than not treated group(9.5±5.8cmvs5.7±4.0cm)(P<0.001). Results showed that height gain was significantly increased as age decreased(<6yrs 13.3±6.1cm, 6-6.9yrs 9.8±5.8cm, 7-7.9yrs 6.6±4.9cm)(p:<0.001). Height gain after end of therapy until final height was significantly higher in cases who were treated at an early age(<6yrs 10.2±6.1cm, 6-6.9yrs 7.1±5.9cm, 7-7.9yrs 5.6±3.9cm, ≥8yrs 4.0±2.9)(P<0.001). Rate of bone age maturation according to age groups were found as 0.6±0.2 for <6 yrs of age, 0.6±0.2 for 6-6.9yrs, 0.8±0.3 for 7-7.9yrs, 0.9±0.4 for ≥8yrs(P<0.001). Pace of bone age advancement was reduced more effectively in those whose therapy started at a younger age. In multivariate linear analysis, most important factors affecting height gain were age of initiation of therapy and target height-SDS.

Conclusion: GnRHa therapy has a positive effect on final height in girls with iCPP whose therapy was started before 8 years of age.This effect becomes more significant as age of initiation of therapy decreases before 7 years of age.Reduction of bone age advancement results in increase in height gain after end of therapy till final height. After 8 years of age, contribution of GnRHa therapy to final height is controversial.