Oestrogen and progesterone across the menopause transition

Menopause is diagnosed by the calendar, not by blood

This is the most useful thing on the page, and it surprises people who have been sold a hormone panel. In a woman over 45 with typical symptoms, menopause is a clinical diagnosis — twelve consecutive months without a period, with no other cause. Major guidelines, including the UK's NICE, advise against routine hormone testing to make it.

The reason is not cost. It is that the tests are genuinely unreliable at the one time people want to use them.

Why the tests fail in perimenopause

Perimenopause is not a slow decline. It is an erratic one. Ovarian output swings widely from cycle to cycle and sometimes within a cycle — oestradiol can be higher than in a young woman one month and very low the next.

So a blood test taken on a Tuesday captures a moment in a system that is oscillating. A normal result does not rule perimenopause out, and a low one does not confirm it. Repeating it produces a different answer, which is a property of the biology rather than of the laboratory.

What each test actually is

• FSH — follicle stimulating hormone, from the pituitary. Rises as the ovaries become less responsive. Useful at the extremes, unreliable in the middle, and suppressed by combined hormonal contraception, which makes it uninterpretable in anyone taking it.
• Oestradiol — the main circulating oestrogen. Varies enormously across a cycle, so a single value needs to be read against where in the cycle it was taken, which in perimenopause may be unknowable.
• Progesterone — rises only after ovulation. Measured around seven days before an expected period, it indicates whether ovulation happened. In an irregular cycle, "seven days before" is a guess.
• AMH — anti‑Müllerian hormone, a measure of remaining ovarian reserve. Used in fertility assessment. It does not predict the date of menopause well enough to plan anything around.

When testing does earn its place

Guidelines carve out real exceptions, and they matter:

• Under 40 with absent or irregular periods — premature ovarian insufficiency is a diagnosis with long‑term consequences and must not be missed. FSH is measured, usually twice, weeks apart.
• Between 40 and 45 with menopausal symptoms, where the picture is less certain.
• After hysterectomy, where there is no bleeding pattern to go on.
• When something else is suspected — thyroid disease and raised prolactin both mimic this picture, and both are easily tested.

That last one is the quiet argument for a thyroid test in any woman presenting with fatigue and change.

If a sample is being taken anyway

1. Note the cycle day, or that there is no longer a cycle. A hormone result without it cannot be read.
2. Morning, and keep to the same hour on repeats.
3. Hormonal contraception suppresses FSH. Say what you are taking.
4. High‑dose biotin interferes with many of these immunoassays. Stop it a few days before and tell the laboratory.
5. One laboratory, if you intend to compare anything over time.

What a panel cannot tell you

It cannot tell you whether to start hormone therapy. That decision rests on symptoms, age, time since the last period, personal and family history, and your own weighing of benefit against risk — not on an oestradiol value. Nor is there a target level to treat towards in ordinary menopausal care.

In our own costing, the women's hormone additions come to roughly ₡65,000 beyond the baseline panel. They are ordered when a question needs them, not by default, and a clinic that sells a standing hormone panel to every woman over 45 is selling tests rather than answering questions.

The boundary

Symptoms in this transition are real and often badly dismissed, and nothing here argues against taking them seriously. The argument is only that the blood test is usually not where the answer lives. That conversation is with a physician who will listen to the history first.