OBJECTIVETo determine the effect of gonadotropin releasing hormone agonist (GnRHa), by itself alone or in combination with recombinant human growth hormone (rhGH), on height in young girls (bone age≥10 years) with idiopathic central precocious puberty (ICPP).

METHODSEighty girls with ICPP (9.0±0.7 years old) from six medical centers across Southeast and Southwest China participated in this study. They were allocated to treatment with GnRHa+rhGH (n=31) and GnRHa (n=49) respectively. Girls in the GnRHa+rhGH group (bone age 11.18 ±0.53 years) were treated with GnRHa for 25.29±6.92 months and rhGH for 12.87±7.02 months. Girls in the GnRHa group (bone age 11.03 ±0.50 years) were treated with GnRHa for 25.96±8.95 months. The height standard deviation for bone age (HtSDS-BA), predicted adult height, near-adult height and net height increase before and after treatment were recorded for girls in both groups.

RESULTSHtSDS-BA was significantly improved after treatment for both groups (P<0.01) and the HtSDS-BA value was superior in the GnRHa+rhGH group over the GnRHa group (P<0.01). Values in near adult height (157±6 cm vs 157±4 cm), net height increase after treatment (4.68 cm vs 3.89 cm), and predicted adult height after drug withdrawal (161±5 cm vs 158±5 cm) were higher in the GnRHa+rhGH group than the GnRHa group, but the differences were not significant.

CONCLUSIONSBoth GnRHa plus rhGH and GnRHa alone can improve the near adult height in girls with ICPP with a bone age ≥10 years to a similar extent. Adult height predicted based on bone age in ICPP girls following drug withdrawal is usually overestimated and precautions should be taken when this parameter is used.