Timing of Hormone Labs for Secondary Infertility Evaluation
For women with secondary infertility, estrogen, LH, and progesterone labs should be drawn at specific times during the menstrual cycle: estradiol and LH on cycle day 3, LH again during mid-cycle (days 12-16), and progesterone 7 days after presumed ovulation (typically day 21 of a 28-day cycle). 1
Optimal Timing for Hormone Testing
Follicular Phase Testing (Early Cycle)
- Baseline hormone evaluation should include FSH, LH, and estradiol drawn on cycle day 3 (or days 2-4) of the menstrual cycle 1
- These early follicular phase measurements help assess ovarian reserve and pituitary function 1
- Abnormal values may indicate diminished ovarian reserve or hypothalamic-pituitary dysfunction 1
Mid-Cycle Testing
- LH should be measured during the expected mid-cycle surge (typically days 12-16 in a 28-day cycle) 2
- Evening urine LH testing correlates well with serum LH peak and can help predict ovulation 2
- For women with irregular cycles, serial testing or home ovulation predictor kits may be needed to identify the LH surge 1
Luteal Phase Testing
- Progesterone should be measured approximately 7 days after presumed ovulation (typically day 21 in a 28-day cycle) 3
- A serum progesterone level >10 ng/mL (>30 nmol/L) confirms ovulation 3
- For women with irregular cycles, progesterone should be timed based on LH surge (7 days after) rather than calendar day 1, 2
Adjustments for Irregular Cycles
- For women with irregular cycles, timing should be adjusted based on cycle length 1
- In cycles <26 or >32 days, standard day 3 and day 21 testing may not accurately reflect hormonal status 1
- Consider monitoring with transvaginal ultrasound to determine follicular development and timing of ovulation in irregular cycles 4
Special Considerations
- Anti-Müllerian hormone (AMH) can be measured on any day of the cycle as it doesn't fluctuate significantly throughout the menstrual cycle 1
- AMH is a valuable marker of ovarian reserve and may help predict timing of menopause 1
- For women with suspected premature ovarian insufficiency, LH, FSH, and estradiol should be measured regardless of cycle day 1
- If central hypogonadism is suspected, additional testing for prolactin levels should be considered 1
Common Pitfalls to Avoid
- Measuring progesterone too early in the luteal phase may give falsely low results that don't reflect peak progesterone production 5
- Hormone measurements during hormonal contraceptive use are not reliable for assessing ovarian function 1
- Single hormone measurements may not be diagnostic; serial measurements may be needed in some cases 1
- Failure to adjust timing of hormone testing for cycle length can lead to misinterpretation of results 1
When to Refer
- Refer to reproductive endocrinology when hormone levels are abnormal or when basic infertility evaluation is normal despite continued inability to conceive 1
- Consider referral when there are signs of ovarian dysfunction or abnormal hormone levels 1
- Early referral is appropriate for women with known risk factors for diminished ovarian reserve 1