Effect of central precocious puberty and gonadotropin-releasing hormone analogue treatment on peak bone mass and final height in females.

UNLABELLED

To evaluate the effect of central precocious puberty (CPP) and its treatment with gonadotropin-releasing hormone (GnRH) analogues on final height and peak bone mass (PBM), we measured lumbar bone mineral density (BMD) in 23 girls at final height. Patients were distributed in two groups. Group 1: 14 patients with progressive CPP were treated with GnRH analogues; seven patients received buserelin (1600 microg/daily), subsequently switched to depot triptorelin (60 microg/kg/26-28 days); seven patients were treated with depot triptorelin (60 microg/kg/26-28 days); mean age of treatment was 6.2 years (range 2.7-7.8 years); the treatment was discontinued at the mean age of 10.1 years (range 8.7-11.3 years); final height was reached at the mean age 13.4 years (range 12.0-14.9 years). Group 2: 9 patients (mean age 6.5 years, range 4.8-7.7 years) with a slowly progressing variant of CPP were followed without treatment; final height was reached at the mean age 13.6 years (range 12.5-14.8 years). Lumbar BMD (L2-L4 by dual energy X-ray absorptiometry) was measured in all patients at final height. In group 1, final height (158.9+/-5.4 cm) was significantly greater than the pre-treatment predicted height (153.5+/-7.2 cm, P < 0.001), but significantly lower than mid-parental height (163.2+/-6.2 cm, P < 0.005). Subdividing the girls of group 1 according to the bone age at discontinuation of therapy (i.e. < or =11.5 years, n=5, or > or =12.0 years, n=9), the former patients had a final height significantly higher than the latter (163.7+/-3.9 cm vs 156.5+/-4.6 cm, P < 0.02). In group 2, final height (161.8+/-4.6 cm) was similar to the pre-treatment predicted height (163.1+/-6.2 cm, P=NS) and was not significantly different from mid-parental height (161.0+/-5.9 cm). BMD values (group 1: 1.11+/-0.14 g/cm2, group 2: 1.22+/-0.08 g/cm2) were not significantly different from those of a control group (1.18+/-0.10 g/cm; n=20, age 16.3-20.5 years) and the patients' mothers (group 1: 1.16+/-0.07 g/cm2, n=11, age 32.9-45.1 years; group 2: 1.20+/-0.08 g/cm2, n=7, age 33.5-46.5 years). In group 1, the girls who stopped therapy at a bone age < or =11.5 years had significantly higher BMD (1.22+/-0.10 g/cm2) compared to those who discontinued therapy at a bone age > or =12.0 years (1.04+/-0.12 g/ cm2, P < 0.05).

CONCLUSION

In girls with progressive CPP, long-term treatment with GnRH analogues improves final height. A subset of patients with CPP does not require treatment because good statural outcome (slowly progressing variant). In CPP, the abnormal onset of puberty and the long-term GnRH analogue treatment do not impair the achievement of PBM. In GnRH treated patients, the discontinuation of therapy at an appropriate bone age for pubertal onset may improve both final height and PBM.