In a 34‑year‑old woman with follicle‑stimulating hormone 5.1 U/L, luteinizing hormone 7.5 U/L, estradiol 130 pmol/L and progesterone <1 nmol/L, what does this hormone profile indicate about her menstrual phase and ovulation status?

Hormone Profile Interpretation: Anovulatory Follicular Phase

This hormone profile indicates the patient is in the early-to-mid follicular phase of her menstrual cycle and has NOT ovulated, as evidenced by the progesterone level <1 nmol/L, which is well below the threshold of 6 nmol/L required to confirm ovulation. 1, 2

Menstrual Phase Assessment

Follicular Phase Confirmation

• FSH 5.1 U/L and LH 7.5 U/L both fall within the normal follicular phase range (FSH 3-10 U/L, LH 2-8 U/L), confirming this patient is in the follicular phase of her cycle. 1
• The oestradiol level of 130 pmol/L is within the follicular phase reference range (50-850 pmol/L), consistent with early follicular activity and developing follicles. 1, 3
• The LH:FSH ratio is 1.47 (7.5/5.1), which is within the normal range of 0.2-1.7 for the follicular phase and does NOT suggest polycystic ovary syndrome (PCOS), which typically shows an LH:FSH ratio >2. 1, 3, 4

Ovulation Status: Anovulation Confirmed

Critical Progesterone Interpretation

• Progesterone <1 nmol/L definitively indicates anovulation or that the sample was taken before ovulation occurred. 1, 2
• Progesterone levels <6 nmol/L indicate anovulation**, while levels **>25 nmol/L are consistent with ovulation. 1
• The mid-luteal progesterone measurement (approximately 7 days post-ovulation, or "day 21" in a 28-day cycle) is the gold standard for confirming ovulation, with a threshold of ≥5 ng/mL (≥16 nmol/L) indicating confirmed ovulation. 2, 3

Timing Considerations

• If this blood draw was intended to assess ovulation (mid-luteal timing), the progesterone <1 nmol/L confirms anovulation for this cycle. 1, 2
• If this blood draw was taken during the follicular phase (days 3-6), then ovulation has simply not yet occurred, and a repeat progesterone measurement should be performed 7 days before expected menses to assess whether ovulation occurs. 2, 3

Clinical Implications and Next Steps

What This Profile Rules Out

• This profile does NOT suggest premature ovarian failure, as FSH is not elevated (would need FSH >35 IU/L and LH >11 IU/L). 1, 3
• This profile does NOT suggest hypothalamic amenorrhea, as LH is not suppressed (would need LH <7 IU/mL). 1, 3
• This profile does NOT strongly suggest PCOS based on the LH:FSH ratio alone, though PCOS remains possible if clinical features (oligomenorrhea, hirsutism, obesity) are present. 1, 3

Essential Follow-Up Actions

• Obtain a detailed menstrual history for the past 6 months to determine if cycles are regular (23-38 days), oligomenorrheic (>35 days), or amenorrheic (>6 months without bleeding). 1
• If cycles are irregular, repeat progesterone measurement during the mid-luteal phase (approximately 7 days before expected menses, NOT fixed "day 21" if cycles are irregular) to definitively assess ovulation status. 2, 3
• If anovulation is confirmed on repeat testing, investigate common causes: PCOS (check testosterone, pelvic ultrasound), hyperprolactinemia (check prolactin), and thyroid dysfunction (check TSH). 1, 3

Critical Pitfall to Avoid

• The single most common error is assuming "day 21" progesterone testing applies to all women. For women with irregular cycles, testing must occur approximately 7 days before expected menses (mid-luteal phase), not on a fixed calendar day. 2, 3
• DHEA supplements can cause false elevation of progesterone assays, though this is not relevant here given the very low level. 1