title: Assessment of gonadotrophin suppression in girls treated with GnRH analogue for central precocious puberty; validity of single luteinizing hormone measurement after leuprolide acetate injection.
abstract: 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.
  
  
  METHODS
  Prospective study.
  
  
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Division of Pediatric Endocrinology, Hacettepe University Medical School, Ankara, Turkey.
authors.forename: Huseyin
authors.initials: H
authors.lastname: Demirbilek
authors.forename: Ayfer
authors.initials: A
authors.lastname: Alikasifoglu
authors.forename: Nazli E
authors.initials: NE
authors.lastname: Gonc
authors.forename: Alev
authors.initials: A
authors.lastname: Ozon
authors.forename: Nurgun
authors.initials: N
authors.lastname: Kandemir
mesh_terms: D002648:Child; D002675:Child, Preschool; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D016729:Leuprolide / Q000008:administration & dosage / Q000627:therapeutic use*; D007986:Luteinizing Hormone / Q000097:blood*; D011446:Prospective Studies; D011629:Puberty, Precocious / Q000188:drug therapy*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D007986:Luteinizing Hormone; D016729:Leuprolide