Which parameters predict the beneficial effect of GnRHa treatment on height in girls with central precocious puberty?

OBJECTIVE: Data about GnRHa on adult height in girls with central precocious puberty (CPP) have shown variable results, ranging from improvement of growth prognosis to lack of any benefit. This study was designed to delineate the criteria to decide which girls with idiopathic CPP (iCPP) will have a height benefit from GnRHa treatment. DESIGN: Retrospective PATIENTS: 102 girls with iCPP who had reached final height (FH) were included. MEASUREMENTS: Auxological, hormonal and radiological findings at treatment onset, and FHs were extracted from records. RESULTS: Most important factor affecting height gain was chronological age (CA) at treatment onset. All the girls treated ≤6.4 years of age achieved a height gain of ≥1SDS, while none of the girls treated ≥8.3 years of age made the target. 75.6% of patients who started GnRHa between the ages of 6.4 and 8.3 years had a height gain of ≥1SDS. Most important factors affecting height gain in those treated 6.4-8.3 years were advanced bone age (BA), basal estradiol (E2 ) and pubertal stage (r2 : 0.906; P < .001). All individuals with BA advancement of ≥2.6 years or E2 of ≥32.6 pg/ml or pubertal stage of ≥3 had significant height gain, and none of the cases with BA advancement of <2 years or E2 of <21.5 pg/ml or pubertal stage of <2 had a height gain of ≥1SDS. CONCLUSIONS: Treatment with GnRHa is unquestionably beneficial to improve FH in girls with iCPP when initiated ≤6.4 years of age. GnRHa treatment after 8.3 years of age may not improve FH. Girls between the ages of 6.4 and 8.3 years at presentation can have a better height gain if BA (≥2.6 years over CA) and pubertal findings (pubertal stage ≥3 or E2 ≥32.6 pg/ml) are well-advanced.

Assessment of gonadotrophin suppression in girls treated with GnRH analogue for central precocious puberty; validity of single luteinizing hormone measurement after leuprolide acetate injection.

OBJECTIVE: Intravenous GnRH stimulation test has often been used as gold standard test for the evaluation of hypothalamic-pituitary-gonadal axis in the diagnosis of central precocious puberty (CPP) and in the assessment of pubertal suppression. However, this test is time-consuming, costly and uncomfortable for the patients. We aimed to analyse the validity of single LH sample 90 min after GnRH analogue (GnRHa) administration in the evaluation of gonadotrophin suppression during CPP therapy and to determine a cut-off level for LH indicating adequate suppression. DESIGN: Prospective study. PATIENTS AND METHODS: One hundred and forty-two patients with CPP were included in this study. Peak LH level during iv GnRH stimulation test after the third dose of GnRHa was compared with LH level 90 min after injection of the 3rd dose of GnRHa. RESULTS: There was a positive correlation between LH level following a GnRHa injection and peak LH during standard iv GnRH stimulation test (r = 0·83; P < 0·0001). A LH value of 2·5 mIU/ml or less 90 min after GnRHa injection was considered to be the cut-off for the determination of pubertal suppression (sensitivity and specificity was 100% and 88%, respectively). In 117 patients, gonadotrophin suppression was existed according to both GnRHa and iv GnRH tests. In 25 patients, gonadotrophin suppression was not found in the GnRHa test. However, 16 of them were suppressed according to the iv GnRH test. CONCLUSION: Single LH determination 90 min after GnRHa administration using a cut-off level of 2·5 mIU/ml reflects pubertal suppression with a high sensitivity and specificity. However, this test may fail to show pubertal suppression in some cases. Those patients who appear to be inadequately suppressed should be reassessed using standard iv GnRH stimulation test for optimal dose adjustment.