Combined therapy with GnRH analog plus growth hormone in central precocious puberty

GnRH analogues (GnRHa) arrest pubertal development, and slow growth velocity (GV) and bone maturation, thus improving adult height in central precocious puberty (CPP). In some patients, however, GV decreases to such an extent that it compromises the improvement in predicted adult height (PAH) and therefore the addition of GH is suggested. Of 20 patients with idiopathic CPP (treated with GnRHa depot-triptorelin] at a dose of 100 microg/kg every 21 days i.m. for at least 2-3 yr) whose GV fell below the 25th percentile for chronological age (CA), ten received, in addition to the GnRHa, GH at a dose of 0.3 mg/kg/wk, s.c. 6 days weekly, for 2-4 yr. Ten patients matched for BA, CA, and duration of GnRHa treatment who showed the same growth pattern but refused GH treatment, served to evaluate the efficacy of the addition of GH. No patient showed classical GH deficiency. Both groups discontinued treatment at a comparable BA (mean +/- SEM): 13.2 +/- 0.2 yr in GnRHa + GH vs 13.0 +/- 0.1 yr in the control group. At the conclusion of the study all the patients had achieved adult height. Adult height was considered to be attained when the growth during the preceding year was less than 1 cm, with a BA of over 15 yr. Patients of the group treated with GH + GnRHa showed an adult height significantly higher (p<0.001) than pretreatment PAH (160.6 +/- 1.3 vs 152.7 +/- 1.7 cm). Height SDS for BA significantly increased from -1.5 +/- 0.2 at start of GnRHa to -0.21 +/- 0.2 at adult height (p<0.001). Target height was significantly exceeded. The GnRH alone treated group reached an adult height not significantly higher than pretreatment PAH (157.1 +/- 2.5 vs 155.5 +/- 1.9 cm). Height SDS for BA did not change (from -1.0 +/- 0.3 at start of GnRHa to -0.7 +/- 0.4 at adult height). Target height was just reached but not significantly exceeded. The gain in centimeters obtained calculated between pretreatment PAH and final height was 7.9 +/- 1.1 cm in patients treated with GH combined with GnRH analogue while in patients treated with GnRH analogue alone the gain was just 1.6 cm +/- 1.2 (p=0.001). Furthermore, no side effects, bone age progression, or ovarian cysts, were observed in GnRHa + GH treated patients. In conclusion, a gain of 7.9 cm in adult height represents a significant improvement which justifies the addition of GH for 2-3 yr to conventional treatment with GnRH analogues in patients with central precocious puberty, and with a decrease in growth velocity so marked as to impair predicted adult height to below the third percentile.