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Appendix 9 – Implants

View HRT Guidance Flow Chart


  • Usual dose is 25 or 50mg every 4-6 months.
  • Avoid more frequent use due to risk of escalation levels of plasma estradiol (‘tachyphylaxis)
  • If symptoms return too early, check plasma estradiol; do not re-implant if > 1000pmol/ℓ
  • For long-term use check serum estradiol every 1-2 years, or if patient requests earlier implant. The results should be below the mid-cycle peak for pre-menopausal women for your laboratory. It is advisable to check prior to every implant and it is not unusual to find a level over 1000 in a woman with an acceptable trough level six months previously. The laboratory may have a mid-cycle peak over 1000 pmol/ℓ.


  • Can be helpful for reduced libido and lethargy
  • Usual dose 100mg every six months if available.
  • ‘Downy’ facial hair and other body hair increase is occasional side-efect; other androgenic side-effects are uncommon