Effects of combined gonadotropin-releasing hormone agonist and growth hormone therapy on adult height in precocious puberty: A further contribution

Out of 35 girls with idiopathic central precocious puberty (CPP) treated with gonadotropin-releasing hormone agonist (GnRHa) (depot-triptorelin) at a dose of 100 mug/kg every 21 days i.m. for at least 2-3 years whose growth velocity fell below the 25(th) percentile for chronological age (CA), 17 received growth hormone (GH) in addition at a dose of 0.3 mg/kg/week, s.c., 6 days per week, for 2-4 years. The other 18, matched for bone age (BA), CA and duration of GnRHa treatment, who showed the same growth pattern but refused GH treatment, remained on GnRHa alone, and were used as a control group to evaluate GH efficacy. No patient was GH deficient. Both groups discontinued treatment at a comparable BA (mean +/- SD): BA 13.4 +/- 0.6 in GnRHa plus GH group vs 13.0 +/- 0.5 years in the GnRHa alone group. The 35 patients have reached adult height (i.e. growth during the preceding year was less than 1 cm, with a BA of over 15 years). Patients of the group treated with GH plus GnRHa showed an adult height (161.2 +/- 4.8 cm) significantly higher (p <0.001) than pre-treatment predicted adult height (PAH) calculated according to tables either for accelerated girls (153.2 +/- 5.0 cm) or for average girls (148.6 +/- 4.3 cm). The adult height of the GnRH alone treated group (156.6 +/- 5.7) was not significantly higher than pre-treatment PAH if calculated on Bayley and Pinneau tables for accelerated girls (153.9 +/- 3.8 cm), whilst it remained significantly higher if calculated on tables for average girls (149.6 +/- 4.0 cm) (p <0.001). The gain between pre-treatment PAH and final height was 8.2 +/- 4.8 cm according to tables for accelerated girls and 12.7 +/- 4.8 cm according to tables for average girls in patients treated with GH plus GnRHa; while in patients treated with GnRH alone the gain calculated between pre-treatment PAH for accelerated girls was just 2.3 +/- 2.9 cm and 7.1 +/- 2.7 cm greater than pre-treatment PAH for average girls. The difference between the gain obtained in the two groups (about 6 cm) remained the same, however PAH was calculated. The addition of GH to GnRHa in a larger cohort of patients with CPP with a longer follow-up confirms the safety of the combined treatment and the still significant but more variable gain in the group with the combined treatment, probably due to the larger number of patients analyzed. Caution is advised in using such an invasive and expensive treatment, and there is need for further studies before widespread clinical use outside a research setting.