When should hormone levels be taken when evaluating for secondary infertility?

Hormone Level Timing for Secondary Infertility Evaluation

Hormone levels for secondary infertility evaluation should be taken on day 3 of the menstrual cycle, with FSH and estradiol being the primary measurements to assess ovarian reserve. 1

Key Hormone Tests and Timing

• FSH and estradiol should be measured on day 3 of the menstrual cycle as the baseline assessment for ovarian reserve 1
• LH, FSH, and estradiol levels should be assessed randomly if the patient has amenorrhea, or during the early follicular phase (days 2-5) if the patient has oligomenorrhea 1
• For patients with irregular cycles, hormone testing should be performed but results interpreted with caution due to menstrual irregularities 1
• Anti-Müllerian hormone (AMH) can be measured on any day of the cycle as it generally does not vary by menstrual day and is not affected by exogenous hormones 1

Specific Hormone Level Interpretation

• Day 3 FSH levels >10 IU/L indicate diminished ovarian reserve in women with normal prognosis 2
• Day 3 FSH levels >8 IU/L may indicate diminished ovarian reserve in women with poor prognosis 2
• Day 3 estradiol levels ≥80 pg/mL are associated with poorer outcomes in fertility treatments, independent of FSH levels 3
• Day 3 estradiol levels ≥56 pg/mL may be a more appropriate cutoff for women with normal prognosis 2

Special Considerations

• For women over 35 years, earlier assessment is justified after 6 months of regular unprotected intercourse rather than waiting 12 months 1
• Women with a history of oligo-amenorrhea, suspected uterine or tubal disease, endometriosis, or with a partner known to be subfertile should also be evaluated earlier 1
• Day 3 hormone levels may vary between cycles, particularly in women over 40 years of age, so repeated testing may be necessary 4
• FSH values vary less between cycle days 2-4 (within 18%) than estradiol values (up to 40%), so minor variations in testing day are acceptable 4

Common Pitfalls and Caveats

• A single normal day 3 FSH level (<20 mIU/mL) in women under 40 is highly predictive of subsequent values within a year, but women aged 40-44 may show significant variations between cycles 4
• Hormone levels should be assessed after discontinuing oral contraceptives or hormone replacement therapy, ideally after two months without these medications 1
• Subtle hormonal abnormalities across the menstrual cycle, such as elevated FSH in early and mid-follicular phases, may indicate diminished ovarian reserve even with normal baseline values 5
• Patients using fertility awareness-based methods should be advised that hormone testing may be less reliable during postpartum, breastfeeding, or perimenopausal periods 1

By following these guidelines for hormone level timing in secondary infertility evaluation, clinicians can accurately assess ovarian reserve and identify potential causes of infertility, allowing for appropriate treatment decisions and referrals when necessary.