title: Urinary N-telopeptides to monitor bone resorption while on GnRH agonist therapy.
abstract: OBJECTIVE
  To assess the utility of urinary cross-linked N-telopeptides in monitoring bone resorption and predicting bone loss during GnRH agonist administration.
  
  
  METHODS
  Ninety patients who were prescribed GnRH agonist therapy for 3-6 months for treatment of endometriosis, leiomyomas or other gynecologic disorders participated in this prospective multicenter study. N-telopeptides, serum estradiol (E2), and bone mineral density were monitored before, during and up to 3 months after the course of GnRH agonist therapy.
  
  
  RESULTS
  N-telopeptide levels increased significantly throughout GnRH agonist therapy and returned to baseline levels by 3 months after treatment was completed. A significant negative correlation was seen between N-telopeptide and E2 measurements after 3 months (r=-0.23, P<.05), 4 months (r=-0.32, P < .05), and 5 months (r=-0.41, P<.005) of GnRH agonist therapy. The percent change in bone mineral density at L1-L4 at 6 months of GnRH agonist treatment correlated inversely with the percent change in N-telopeptides from baseline to 2,3,4, and 5 months of treatment; the percent change of bone mineral density at the femoral neck at 6 months correlated inversely with the percent change of N-telopeptides from baseline to month 4.
  
  
  CONCLUSIONS
  Urinary N-telopeptide determinations provide a quantitative measure of bone resorption, due to GnRH agonist-induced hypoestrogenism. Increases in resorption as measured by N-telopeptides parallel decreases in in E2 levels. Increases in N-telopeptides on GnRH agonist therapy may provide a tool to predict decreases in bone mineral density.
authors.affiliation: Section of Reproductive Endocrinology, Virginia Mason Medical Center, Seattle, WA, USA.
authors.forename: L A
authors.initials: LA
authors.lastname: Marshall
authors.forename: D F
authors.initials: DF
authors.lastname: Cain
authors.forename: W P
authors.initials: WP
authors.lastname: Dmowski
authors.forename: C H
authors.initials: CH
authors.lastname: Chesnut
mesh_terms: D000328:Adult; D018931:Antineoplastic Agents, Hormonal / Q000494:pharmacology / Q000627:therapeutic use*; D015519:Bone Density / Q000187:drug effects; D001862:Bone Resorption; D003094:Collagen / Q000652:urine*; D024042:Collagen Type I; D004715:Endometriosis / Q000188:drug therapy; D004958:Estradiol / Q000097:blood; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D005833:Genital Neoplasms, Female / Q000188:drug therapy* / Q000503:physiopathology; D007987:Gonadotropin-Releasing Hormone / Q000819:agonists*; D017273:Goserelin / Q000494:pharmacology / Q000627:therapeutic use; D006728:Hormones / Q000494:pharmacology / Q000627:therapeutic use; D006801:Humans; D007889:Leiomyoma / Q000188:drug therapy / Q000503:physiopathology; D016729:Leuprolide / Q000494:pharmacology / Q000627:therapeutic use*; D008875:Middle Aged; D017274:Nafarelin / Q000494:pharmacology / Q000627:therapeutic use; D010455:Peptides / Q000652:urine*; D011446:Prospective Studies; D014594:Uterine Neoplasms / Q000188:drug therapy / Q000503:physiopathology
chemical_list: D018931:Antineoplastic Agents, Hormonal; D024042:Collagen Type I; D006728:Hormones; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D017273:Goserelin; D017274:Nafarelin; D007987:Gonadotropin-Releasing Hormone; D004958:Estradiol; D005640:Follicle Stimulating Hormone; D003094:Collagen; D016729:Leuprolide