In a 39‑year‑old woman being evaluated after tubal reversal, should we order a day‑3 luteinizing hormone (LH) level now?

Day-3 LH Testing in Post-Tubal Reversal Evaluation

Yes, ordering a day-3 LH level is prudent and should be performed alongside FSH and estradiol as part of the baseline ovarian reserve assessment in this 39-year-old woman. 1, 2

Rationale for Day-3 LH Testing

Diagnostic Value of Low LH

• **Low LH levels (<3 IU/L) predict poor ovarian response to stimulation**, with women showing significantly fewer follicles >15 mm diameter (2.6 vs 3.6, P=0.004) and lower peak estradiol levels (703 vs 955 ng/ml, P=0.005) compared to those with LH >3 IU/L 3

• Low day-3 LH indicates hypothalamic amenorrhea (hypogonadotropic hypogonadism), which occurs in approximately 12% of women with certain conditions versus 1.5% in the general population, and can cause menstrual irregularities and infertility 2

• The combination of low LH with normal FSH suggests inadequate GnRH pulsatility, which directly impairs follicular recruitment and may require supplementation strategies if assisted reproduction becomes necessary 2, 3

Diagnostic Value of Elevated LH/FSH Ratio

• An LH/FSH ratio >2 is diagnostic of polycystic ovary syndrome (PCOS), which affects 4-6% of women in the general population and is a common cause of anovulation 1, 4

• PCOS manifests as hypersecretion of LH, ovarian hyperactivity, and FSH hypofunction, resulting in hyperandrogenism and ovarian acyclicity that would significantly impact post-reversal fertility 1

• Measuring the LH/FSH ratio on cycle days 3-6 allows early identification of PCOS, enabling timely intervention before attempting conception 4

Complete Day-3 Hormonal Panel

The following tests should be obtained simultaneously on cycle days 3-6:

• FSH measurement (calculation based on average of three estimations taken 20 minutes apart if possible) - FSH >35 IU/L indicates ovarian failure; FSH >11 IU/L suggests diminished reserve 1

• LH measurement - LH >11 IU/L is abnormal; LH <3 IU/L predicts poor stimulation response 1, 3

• Estradiol level - to assess baseline ovarian activity and rule out falsely reassuring FSH in the setting of elevated estradiol 5

• Calculate LH/FSH ratio - ratio >2 suggests PCOS 1, 4

Additional Essential Testing

Beyond the day-3 panel, the following evaluations are critical:

• Mid-luteal phase progesterone (blood taken during mid-luteal phase according to menstrual cycle) - levels <6 nmol/l indicate anovulation, commonly caused by PCOS 1, 4

• Morning resting prolactin (not postictal) - levels >20 μg/l are abnormal and may suppress LH/FSH secretion; rule out hypothyroidism or pituitary tumor 1, 2

• Testosterone and androstenedione (measured on cycle days 3-6) - testosterone >2.5 nmol/l or androstenedione >10.0 nmol/l suggests PCOS or other hyperandrogenic conditions 1, 4

• Fasting glucose/insulin ratio - ratio >4 suggests reduced insulin sensitivity associated with obesity and PCOS 1, 4

• Transvaginal pelvic ultrasound (performed on days 3-9 of cycle) - >10 peripheral cysts (2-8 mm diameter) with thickened ovarian stroma indicates polycystic ovaries 1, 4

Clinical Implications for Age 39

At age 39, this patient faces time-sensitive fertility considerations where baseline ovarian reserve assessment directly impacts treatment planning:

• Day-3 FSH levels predict IVF outcomes, with FSH <15 mIU/ml yielding 17.0% ongoing pregnancy rates versus 3.6% with FSH >25 mIU/ml 5

• Low day-3 LH (<3 IU/L) may require higher FSH dosing during ovarian stimulation to achieve adequate follicular response 6

• The combination of advanced maternal age and abnormal day-3 hormones would accelerate the decision to proceed with assisted reproductive technology rather than prolonged expectant management 2

Common Pitfalls to Avoid

• Do not order LH in isolation - interpretation requires simultaneous FSH and estradiol for meaningful clinical context 1, 5

• Timing is critical - LH must be measured on cycle days 3-6; measurements outside this window are not interpretable for ovarian reserve assessment 1, 4

• Single measurements can be misleading - if possible, obtain average of three samples taken 20 minutes apart for FSH/LH, though this is often impractical in clinical practice 1

• Do not dismiss borderline values - even LH values of 3-5 IU/L may predict suboptimal response, though the strongest evidence exists for the <3 IU/L threshold 3, 6

• Prolactin must be checked - hyperprolactinemia suppresses GnRH pulsatility and can cause inappropriately low LH/FSH despite normal ovarian function 1, 2