title: Letrozole administration during the luteal phase after ovarian stimulation impacts corpus luteum function: a randomized, placebo-controlled trial.
abstract: OBJECTIVE
  To investigate the effect of letrozole-an oral aromatase inhibitor-on E(2), P, and LH levels when administered during the luteal phase after oocyte retrieval in IVF/intracytoplasmic sperm injection (ICSI) cycles.
  
  
  METHODS
  Prospective, randomized, placebo controlled trial.
  
  
  METHODS
  University-affiliated private reproductive medicine center.
  
  
  METHODS
  Thirty oocyte donors undergoing standardized controlled ovarian hyperstimulation (COH) protocols.
  
  
  METHODS
  Patients were randomized after successful egg retrieval to receive either 2.5 mg of letrozole (Femara; Novartis, Barcelona, Spain) or a placebo (folic acid tablets). All donors were under intrauterine device (IUD) contraception.
  
  
  METHODS
  Serum E(2), P, and LH the day of hCG administration and days +4, +7 and +10 after ovum pick-up.
  
  
  RESULTS
  Donors had a comparable serum E(2) level on the day of hCG administration (1,858 vs. 2,143 pg/mL). Interestingly, levels dramatically dropped 4 days after egg retrieval, reaching a statistically significant lower level in those receiving letrozole (279 vs. 1,586 pg/mL). Again, at the next time points serum E(2) levels were significantly lower (day +7: 240 vs. 855 pg/mL and day +10: 40 vs. 448 pg/mL). No significant differences were observed in P levels, but LH serum concentrations were lower in the control group on day +7 (0.18 vs. 0.02 mIU/mL and day +10 (0.40 vs. 0.16 mIU/mL), when serum E(2) levels were higher.
  
  
  CONCLUSIONS
  The administration of 2.5 mg of letrozole during the luteal phase has an impact on corpus luteum (CL) function. It reduces serum E(2) levels, which allows a faster recovery of LH concentration. This may be of interest not only for egg donors, but also in patients at high risk of ovarian hyperstimulation syndrome (OHSS) who freeze all their embryos or who cancel hCG administration to reduce the potential risk that high E(2) levels pose.
authors: IVI-Madrid, Santiago de Compostela 88, Madrid, Spain. jgvelasco@ivi.es
authors: Juan A
authors: JA
authors: Garcia-Velasco
authors: Guillermo
authors: G
authors: Quea
authors: Manuel
authors: M
authors: Piró
authors: Mercedes
authors: M
authors: Mayoral
authors: María
authors: M
authors: Ruiz
authors: Mónica
authors: M
authors: Toribio
authors: Antonio
authors: A
authors: Requena
mesh_terms: D047072:Aromatase Inhibitors / Q000627:therapeutic use*; D003338:Corpus Luteum / Q000187:drug effects / Q000502:physiology*; D004958:Estradiol / Q000097:blood; D005260:Female; D006801:Humans; D007434:Intrauterine Devices; D000077289:Letrozole; D008183:Luteal Phase / Q000187:drug effects / Q000502:physiology*; D007986:Luteinizing Hormone / Q000097:blood; D009570:Nitriles / Q000627:therapeutic use*; D018587:Oocyte Donation; D054315:Oocyte Retrieval / Q000379:methods; D010919:Placebos; D011374:Progesterone / Q000097:blood; D014019:Tissue Donors; D014230:Triazoles / Q000627:therapeutic use*
chemical_list: D047072:Aromatase Inhibitors; D009570:Nitriles; D010919:Placebos; D014230:Triazoles; D011374:Progesterone; D004958:Estradiol; D000077289:Letrozole; D007986:Luteinizing Hormone