The menopausal transition is the stretch of years before periods stop for good, when the body starts changing while cycles are still happening. Sleep gets patchy. Cycles drift. Something feels different, but a blood test comes back looking unremarkable — and the appointment ends without a clear answer.
I used to assume a hormone panel was the reliable way to know. Read the guidelines, though, and the recommendation runs the other way. For most women in the usual age range, the major bodies say the test isn’t needed at all.
The staging system is built on cycles, not hormones
Researchers from several countries agreed on a common framework in 2011, known as STRAW+10, and it remains the reference for describing where someone is in reproductive aging[1]. It divides the reproductive years into three broad periods and anchors everything to the final menstrual period, counting forward and backward from that point[1].
The part worth noticing: the primary criterion for each stage is menstrual cycle change, not a hormone value[1]. Blood work plays a supporting role.
In the early transition, cycles that were previously regular start varying by seven days or more. In the late transition, gaps of 60 days or longer appear, and this stage typically falls one to three years before the final period[1]. Hot flushes and night sweats commonly become noticeable around this point[1].
So “I’m still getting periods, so this isn’t it yet” doesn’t hold up. Once the pattern starts shifting, the transition has already begun.
Estrogen doesn’t taper — it swings
This is the part I had wrong.
I pictured a gentle downward slope. What actually happens is closer to turbulence. Estradiol during the transition fluctuates considerably, and at some points reaches concentrations higher than those seen in women under 35[3].
That reframes a lot. Breast tenderness, unusually heavy bleeding, a month that feels fine followed by one that doesn’t — these read differently once you know the pattern is erratic rather than simply diminishing. The problem in this window is instability more than deficiency.
The steady decline arrives later. Estradiol continues falling for roughly two years after the final period before levelling off[2].
FSH rises first, and keeps rising
As ovarian function declines, the pituitary compensates by releasing more follicle-stimulating hormone. That rise shows up earlier and more distinctly than the estrogen changes.
In the early transition, FSH is elevated but variable[1]. By the late transition it climbs above 25 IU/L[1]. After the final period it keeps rising for about two years before stabilising[2].
Rising FSH alongside swinging estradiol — that combination *is* the transition. It’s a body recalibrating, not simply running out.
Three guideline bodies, one conclusion
Here’s where the international picture gets interesting, because organisations that often differ end up agreeing.
NICE (United Kingdom) advises identifying perimenopause and menopause in otherwise healthy women aged 45 and over on the basis of symptoms alone, without laboratory tests[4]. It goes further, specifically advising against using AMH, inhibin, estradiol, antral follicle count or ovarian volume for this purpose in that age group[4]. Serum FSH is reserved for women aged 40 to 45 with symptoms, or those under 40 with suspected menopause[4].
The British Menopause Society, in a 2026 fact sheet, states that for women in the typical menopause age range of 45 to 55, such tests are generally not required to diagnose perimenopause or menopause, to monitor hormone therapy, or to manage symptoms[5].
ACOG and the North American Menopause Society likewise recommend a symptom-based approach and caution against interpreting hormone numbers in isolation.
The reasoning is the same everywhere: FSH swings substantially over short periods, and the numbers don’t track the severity or duration of symptoms[4]. A single draw is a snapshot of a moving target.
If you’re in Korea, here’s what to expect
For readers living here, the practical picture differs from what you may be used to at home — though it lands in a similar place.
Korea’s health insurance review committee has set out what is reimbursable for menopause-related hormone testing. For diagnosing menopause, FSH alone is recognised, with estradiol added only in cases of early menopause[6]. If the first test isn’t conclusive, one repeat is allowed, though for women aged 55 and over menopause is presumed and additional testing requires specific justification[6].
Notably, LH is not reimbursed, on the basis that it doesn’t affect diagnosis or treatment[6]. FSH testing during ongoing hormone therapy isn’t covered either[6]. The stated rationale is that ovarian function and estrogen output fluctuate over years, so a single-timepoint measurement is an unreliable read of ovarian function[6].
Two things follow. First, if your Korean lab slip lists only FSH, that isn’t a shortcut — it reflects how the system is designed. Second, Korea reached the same conclusion as NICE and the BMS by an entirely different route: clinical evidence in one case, reimbursement policy in the other.
One more piece of local context. Western sources typically cite a median final period around 51.4 years[3]. A study analysing 4,485 naturally postmenopausal women from Korea’s national health and nutrition survey put the average at 49.9 years[7]. That’s roughly eighteen months earlier. Since the transition begins several years before the final period, it means the whole process may start earlier than the timeline your friends back home are working from.
When testing does make sense
None of this means hormone testing is pointless. It means it earns its place in specific situations.
- Under 45, and especially under 40, where premature or early menopause is a possibility[4]
- When symptoms could be something else — thyroid disease overlaps considerably with this picture, and fatigue can trace back to anemia or low B12
- When the result would change what happens next — a test that won’t alter the plan is worth questioning
Also worth knowing: if you’re using combined estrogen-progestogen contraception or high-dose progestogen, FSH results are affected and shouldn’t be relied on[4].
What to bring instead
If the guidelines rest on symptoms and cycle change, then the most useful thing you can hand a clinician is a record of exactly that.
Dates of periods. A note on how the flow compared to usual. A line about sleep, temperature, mood. Nothing elaborate — a few words per entry is enough. Over three or four months this becomes far more informative than a single blood draw, and it travels well if you end up seeing a doctor in a different country.
Closing
The transition is easier to sit with once you stop expecting a number to define it. What’s happening isn’t a steady decline but a period of instability, and that’s precisely why a snapshot struggles to capture it.
I came into this assuming testing was the rigorous approach and symptom-based diagnosis was the rough one. It’s the reverse. The guidelines aren’t cutting corners — they’re acknowledging that the measurement is less stable than the pattern.
Next in this series: what the approved functional claims for menopause supplements actually cover, and how Korea’s framework compares with the US and EU.
At a Glance
- STRAW+10 stages the transition primarily by menstrual cycle change, with hormones as supporting evidence
- Estradiol fluctuates rather than declining smoothly, and can exceed levels seen in women under 35
- FSH rises earlier and more distinctly, exceeding 25 IU/L in the late transition
- NICE, the British Menopause Society, ACOG and NAMS all favour symptom-based diagnosis for women 45 and over
- In Korea, insurance recognises FSH for diagnosis but not LH, on the grounds that single-timepoint measurement is unreliable
- Average age at natural menopause in Korea is reported at 49.9 years, earlier than commonly cited Western figures
※ This article is for general information and does not replace medical diagnosis or treatment. If bleeding patterns change markedly, if symptoms interfere with daily life, or if you are under 45 and periods have stopped, please see a clinician. Do not interpret lab values on your own or adjust medication or supplements based on them.
References
- StatPearls, “Menopause”, NCBI Bookshelf, https://www.ncbi.nlm.nih.gov/books/NBK507826/
- American Society for Reproductive Medicine, “Executive summary of the Stages of Reproductive Aging Workshop +10”, https://www.asrm.org/practice-guidance/practice-committee-documents/executive-summary-of-the-stages-of-reproductive-aging-workshopd10-addressing-the-unfinished-agenda-of-staging-reproductive-aging-2012/
- “The menopausal transition”, Fertility and Sterility, https://www.sciencedirect.com/science/article/pii/S0015028208037199
- NICE, “Menopause: identification and management (NG23)” — Recommendations, https://www.nice.org.uk/guidance/ng23/chapter/recommendations
- British Menopause Society / Women’s Health Concern, “Hormone blood tests in the menopause transition” fact sheet (2026), https://thebms.org.uk/2026/06/new-whc-fact-sheet-hormone-blood-tests-in-the-menopause-transition/
- Health Insurance Review and Assessment Service committee, reimbursement criteria for menopause-related hormone testing, https://www.medifonews.com/news/article.html?no=40684
- Korea National Health and Nutrition Examination Survey (KNHANES), https://knhanes.kdca.go.kr/