title: The importance of endogenous feedback for monofollicular growth in low-dose step-up ovulation induction with follicle-stimulating hormone in polycystic ovary syndrome: a randomized study.
abstract: OBJECTIVE
  To evaluate the role of endogenous feedback in monofollicular growth during low-dose gonadotrophin therapy in polycystic ovary syndrome (PCOS) by measuring FSH levels in a group of patients cotreated with a GnRH agonist (GnRH-a) (group B) compared with patients not cotreated with an agonist (group A).
  
  
  METHODS
  Prospective randomized study.
  
  
  METHODS
  University tertiary care Reproductive Endocrinology Unit.
  
  
  METHODS
  Women with clomiphene citrate-resistant PCOS.
  
  
  METHODS
  Follicle-stimulating hormone, E2, and inhibin levels, follicular growth.
  
  
  RESULTS
  In group A, FSH levels decreased significantly from 7.3 mIU/mL (conversion factor to SI unit, 1.00) at day -5 to 5.9 mIU/mL at day 0 (day that hCG was administered) despite a constant dose, whereas they remained at a level of 7.4 mIU/mL in group B. The rate of monofollicular growth was significantly higher in group A (80%) than in group B (22%). No significant differences in E2 levels or inhibin levels were found between the groups.
  
  
  CONCLUSIONS
  The absence of a decrease of FSH during GnRH-a treatment in association with a lower rate of monofollicular growth suggests that endogenous feedback during low-dose step-up ovulation induction in PCOS plays an important role. The absence of this feedback mechanism in the presence of normal inhibin levels suggests that negative feedback control by inhibin during follicular stimulation is minimal.
authors.affiliation: Department of Obstetrics and Gynaecology, University Hospital Vrije Universiteit, Amsterdam, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: van der Meer
authors.forename: P G
authors.initials: PG
authors.lastname: Hompes
authors.forename: F
authors.initials: F
authors.lastname: Scheele
authors.forename: E
authors.initials: E
authors.lastname: Schoute
authors.forename: C
authors.initials: C
authors.lastname: Popp-Snijders
authors.forename: J
authors.initials: J
authors.lastname: Schoemaker
mesh_terms: D000328:Adult; D004958:Estradiol / Q000097:blood; D005246:Feedback; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood / Q000627:therapeutic use*; D006801:Humans; D007265:Inhibins / Q000097:blood; D006080:Ovarian Follicle / Q000254:growth & development*; D010062:Ovulation Induction; D011085:Polycystic Ovary Syndrome / Q000188:drug therapy* / Q000503:physiopathology; D011446:Prospective Studies; D017329:Triptorelin Pamoate / Q000627:therapeutic use
chemical_list: D017329:Triptorelin Pamoate; D004958:Estradiol; D007265:Inhibins; D005640:Follicle Stimulating Hormone