From the Research
Letrozole is the preferred first-line ovulation induction agent for women with PCOS, and it should be started with 2.5 mg daily for 5 days, typically on cycle days 3-7 after spontaneous or progesterone-induced menses, as evidenced by the most recent study 1.
Key Considerations for Letrozole Prescription
- Before prescribing letrozole, confirm the diagnosis of anovulatory PCOS, rule out pregnancy, and evaluate for contraindications including liver dysfunction, uncontrolled thyroid disorders, and hypersensitivity to letrozole, as suggested by previous studies 2, 3, 4, 5.
- Baseline testing should include TSH, prolactin, and assessment of ovarian reserve, as recommended by various studies 2, 3, 4, 5.
- Counsel patients about the 40-80% ovulation rate per cycle and potential side effects including headaches, hot flashes, and fatigue, as reported in the literature 2, 3, 4, 5.
- Advise patients that letrozole is used off-label for ovulation induction and has a short half-life (45 hours), with minimal risk of multiple pregnancies (5-7%) or ovarian hyperstimulation syndrome compared to clomiphene citrate, as supported by the evidence 2, 3, 4, 5.
Monitoring and Adjusting Letrozole Treatment
- Monitor for ovulation using transvaginal ultrasound to track follicular development, with the goal of producing 1-2 dominant follicles (≥18 mm), as recommended by the studies 2, 3, 4, 5.
- If ovulation doesn't occur, increase the dose to 5 mg daily for 5 days in the next cycle, and if needed, to 7.5 mg daily (maximum dose), as suggested by the most recent study 1.
- Extending letrozole treatment duration is effective in inducing ovulation in women with PCOS and letrozole resistance, as evidenced by the study 1.
Important Considerations
- Treatment should be limited to 6 ovulatory cycles before considering alternative approaches, as recommended by the literature 2, 3, 4, 5.
- Letrozole works by temporarily inhibiting estrogen production, which increases FSH release and stimulates follicular development, as supported by the evidence 2, 3, 4, 5.