Evaluation of serum kisspeptin levels in girls in the diagnosis of central precocious puberty and in the assessment of pubertal suppression.

BACKGROUND: Onset of puberty is dependent on pulsatile secretion of gonadotropin releasing hormone (GnRH). The kisspeptin-GPR54 signaling system has a considerable role in GnRH physiology and induction of puberty. OBJECTIVES: To evaluate kisspeptin levels in girls with central precocious puberty (CPP) at the time of the diagnosis and during follow-up, to determine whether or not kisspeptin may serve as a marker for diagnosis and follow-up of CPP. PATIENTS AND METHODS: Kisspeptin levels of 28 girls with CPP were measured at the time of diagnosis and repeated at the 6th month of therapy after complete pubertal suppression and compared to kisspeptin levels of 13 age-matched prepubertal controls. RESULTS: Kisspeptin levels of girls with CPP (10.2 +/- 2.6 pg/mL) were higher than those in controls (8.6 +/- 1.5 pg/mL (p = 0.019). There was a significant decline in the kisspeptin levels (7.3 +/- 1.3 pg/mL) of girls with CPP after pubertal suppression (p < 0.0001). CONCLUSION: These findings suggest that kisspeptin levels can be used as corroborative evidence for diagnosis of CPP and a valuable parameter for monitoring treatment efficacy.

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.