title: Dose effects of progesterone in add-back therapy during GnRHa treatment.
abstract: OBJECTIVE
  To compare 1 mg norethisterone acetate with 5 mg norethindrone when used in conjunction with 2 mg estradiol given as add-back therapy during treatment with a gonadotropin-releasing hormone agonist (GnRHa).
  
  
  METHODS
  A prospective, double-blind, randomized study was conducted in a university-based teaching hospital. Forty-seven patients with pelvic endometriosis were recruited. Subcutaneous GnRHa was administered at 6-week intervals, and add-back therapy was commenced with the second dose of GnRHa. Group A patients received 2 mg estradiol and 1 mg norethisterone acetate, while group B patients received 2 mg estradiol and 5 mg norethindrone daily. Changes in bone mineral density, menopausal symptoms, lipid profile and occurrence of breakthrough bleeding were assessed before and after treatment.
  
  
  RESULTS
  Patients in group A had no significant bone loss and satisfactory control of menopausal symptoms. The additional dose of progestogen in group B had a deleterious effect on the lipid profile and increased the frequency of breakthrough bleeding.
  
  
  CONCLUSIONS
  In this study, the benefits of add-back therapy during GnRHa treatment were not enhanced, and a deleterious effect upon the lipid profile was seen when using a constant dosage of 2 mg estradiol and 5 mg norethindrone as compared to 1 mg norethisterone acetate.
authors.affiliation: Department of Obstetrics and Gynaecology, Prince of Wales Hospital, Hong Kong. thcheung@cuhk.edu.hk
authors.forename: Tak-Hong
authors.initials: TH
authors.lastname: Cheung
authors.forename: Keith Wing-kit
authors.initials: KW
authors.lastname: Lo
authors.forename: So-Fan
authors.initials: SF
authors.lastname: Yim
authors.forename: Christopher
authors.initials: C
authors.lastname: Lam
authors.forename: Edith
authors.initials: E
authors.lastname: Lau
authors.forename: Christopher
authors.initials: C
authors.lastname: Haines
mesh_terms: D000328:Adult; D015519:Bone Density / Q000187:drug effects; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D004715:Endometriosis / Q000188:drug therapy*; D004958:Estradiol / Q000008:administration & dosage*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage* / Q000819:agonists*; D006801:Humans; D050356:Lipid Metabolism; D008595:Menorrhagia / Q000188:drug therapy; D009640:Norethindrone / Q000008:administration & dosage*; D011446:Prospective Studies; D016896:Treatment Outcome
chemical_list: D007987:Gonadotropin-Releasing Hormone; D004958:Estradiol; D009640:Norethindrone