Adult Height in Girls with Central Precocious Puberty Treated with Gonadotropin-Releasing Hormone Analogues and Growth Hormone

GnRH analogues (GnRHa) represent the treatment of choice in central precocious puberty (CPP), because arresting pubertal development and reducing either growth velocity (GV) or bone maturation (BA) should improve adult height. However, in some patients, GV decrease is so remarkable that it impairs predicted adult height (PAH); and therefore, the addition of GH is suggested. Out of twenty subjects with idiopathic CPP (treated with GnRHa depot-triptorelin, at a dose of 100 microg/kg im every 21 days, for at least 2-3 yr), whose GV fall below the 25th percentile for chronological age, 10 received, in addition to GnRHa, GH at a dose of 0.3 mg/kg x week s.c., 6 days weekly, for 2-4 yr; and 10 matched for BA, chronological age, and duration of GnRHa treatment, who showed the same growth pattern but refused GH treatment, served to evaluate the efficacy of GH addition. No patient showed classical GH deficiency. Both groups discontinued treatment at a comparable BA (mean +/- SEM): 13.2 +/- 0.2 in GnRHa plus 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 plus GnRHa showed an adult height significantly higher (P < 0.001) than pretreatment PAH (160.6 +/- 1.3 vs. 152.7 +/- 1.7 cm). Target height (TH) was significantly exceeded. The group treated with GnRH alone reached an adult height not significantly higher than pretreatment PAH (157.1 +/- 2.5 vs. 155.5 +/- 1.9 cm). TH 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 GnRHa; whereas in patients treated with GnRHa alone, the gain was just 1.6 +/- 1.2 cm (P = 0.001). Furthermore, no side effects have been observed either on bone age progression or ovarian cyst appearance and the gynecological follow-up in the GH-treated patients (in comparison with those treated with GnRHa alone). 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 during the conventional treatment with GnRHa, especially in patients with CPP, and a decrease in GV so marked as to impair PAH, not allowing it to reach even the third centile.