When your capacity changes before your bloods do.
Sleep breaks up, a word goes missing mid-sentence, and the margin for a hard week gets thinner, often years before a blood test moves. That gap has a name, and it can be measured.
Perimenopause usually begins in the mid-to-late forties and can run for several years before periods stop. Sleep, memory, mood and body composition often change early in that window while standard blood tests still come back normal, because the hormones involved swing widely from one week to the next.
A single FSH or oestradiol result shows one day in a system that is fluctuating. More useful are a record of cycles and symptoms over months, markers that change more steadily, such as AMH, and the markers of what the transition affects further down the line: lipids and ApoB, insulin, iron, thyroid function and bone density. Each is best read against your own earlier results.
Frequent hot flushes and night sweats lasted a median of 7.4 years, and longer than 11.8 years in women whose symptoms began before or early in the transition.
Trouble falling asleep and staying asleep rises step by step through the transition.
In late perimenopause, women stopped improving with practice on memory and processing-speed tests. The effect reversed after menopause.
At the start of the transition, the rate of fat gain doubled and lean mass began to fall, with no change in the rate of weight gain on the scales.
LDL cholesterol and ApoB rise sharply within a year either side of the final period, a change linked to menopause rather than to age.
Still performing, on a thinner margin.
She is usually somewhere between 44 and 52, running a team or a business, and still delivering. What has changed is harder to point at. Waking at 3am and lying there until the alarm. A name or a word that was always there, gone in the middle of a sentence in front of the board. A week that used to be demanding now flattening her by Thursday. Less patience, slower recovery, a waistline that shifted without the scales moving much.
Periods may still be fairly regular. The blood tests come back normal. And somewhere in that conversation the phrase arrives: normal for your age.
This is common enough that close to nine in ten women seek advice about it at some point.1 That doesn’t make it minor. Among women with no history of depression, high depressive symptom scores were more than four times as likely during the transition as before it.2 And it tends to start before anyone thinks to test for it.
A system that swings looks normal on any given day.
The international staging system for reproductive ageing, STRAW+10, defines the start of the transition by cycle pattern: a persistent change of seven days or more in cycle length. Hormone levels aren’t part of that definition, because none of them does the job reliably on its own.3
The reason shows up when hormones are sampled often. An Australian study took blood three times a week across a full cycle in women at each stage. As the transition progressed, FSH rose, but so did oestradiol in ovulating cycles, while progesterone in the second half of the cycle fell and cycles without ovulation became more common.4 Early on, oestradiol can run high one week and low the next.
So a morning blood draw catches one point on a moving line. Taken on a settled day, it looks normal. Taken on a high-oestrogen day, it can even look reassuring. Meanwhile the symptoms track the swings themselves: falling oestradiol and rising FSH were each linked to more trouble falling and staying asleep in a large community study.5
A normal result says the day was normal. It says little about the month.
The changes that arrive early.
Sleep. In more than 3,000 women followed for seven years, the odds of difficulty falling and staying asleep rose as the transition progressed, and more frequent night sweats added to it.5 Night sweats are not brief either: frequent symptoms lasted a median of 7.4 years, and longest in women whose symptoms started before or early in the transition.6
Recall and processing speed. The same research cohort tested cognition each year. Most women got a little better with repeated testing, as people do. Women in late perimenopause did not: their scores for processing speed and delayed recall stopped improving. After menopause, the improvement came back.7 The word that goes missing mid-meeting is measurable, and it appears to be time-limited. For how this overlaps with other causes, see our piece on brain fog after 40.
Body composition. Scanning women through the transition, researchers found that at its start the rate of fat gain doubled and lean mass began to decline, continuing until about two years after the final period. The rate of weight gain did not change.8 The scales stay quiet while the body changes shape. That shift is part of why insulin resistance in women over 40 often appears in this window.
Lipids and bone. Of all the cardiovascular markers tracked, only total cholesterol, LDL and ApoB jumped within a year either side of the final period, a pattern tied to menopause rather than to age.9 Bone density loss began about a year before the final period. Of the 10.6% lost from the spine over ten years, 7.4% went in the three years around the final period.10 Neither of these can be felt.
A comparison, not a measurement.
A reference range describes the middle of a population. An age-adjusted range compares you with other women your age, and at 47 many of them are going through the same transition. Being normal for your age means you look like your peers. It does not tell you whether you have changed from your own 42.
That second question is the one that matters, and it can only be answered with your own earlier numbers. An ApoB that has climbed 20% in two years can still sit inside the range. So can a fasting insulin that has doubled. The range tells you where you sit among other people. Your trend tells you what is happening to you. We cover the difference in more detail in optimal versus reference ranges.
Measuring through a transition.
Some markers show where you are in the transition. Others show what it is doing to the rest of you. Both are worth having, and most are best tracked over time.
| Marker | What it shows | Read it with care because |
|---|---|---|
| Cycle and symptom record | Where you are in the transition | It needs months of entries, not one morning |
| FSH and oestradiol | Ovarian signalling on the day | Both swing week to week in perimenopause |
| AMH | Remaining ovarian reserve and likely timing | It gives a probability, not a date |
| Lipids and ApoB | The cardiovascular shift around the final period | A rise can stay inside the range |
| Fasting insulin and HbA1c | Early metabolic change | Glucose alone is often the last to move |
| Iron studies | Iron lost to heavier or closer periods | Low ferritin mimics transition fatigue |
| Thyroid function | A common cause of overlapping symptoms | Fatigue and mood changes have more than one source |
| Bone density | A baseline before the fastest loss | Loss starts before the final period |
Read the transition as a trend.
Of the hormone markers, AMH is the most useful for timing because it falls steadily instead of swinging. In women followed to their final period, AMH predicted when that period would come better than FSH did. An AMH below 10 pg/mL meant a 51% to 79% chance of the final period within a year, depending on age. Above 100 pg/mL, 90% to 97% of women had not reached it within a year.11 It’s a planning tool. Knowing the final period is probably a year or two away puts a hard year in context.
The rest of the picture is about what to watch. The lipid rise, the change in body composition and the early bone loss all happen quietly, inside a window that can be predicted. A baseline taken early, and repeated, means you see them coming. How hormones are cleared matters too, which is where a look at sex hormone metabolism adds a layer a blood level can’t.
The transition itself is normal. What it does to sleep, recall, metabolism and bone is measurable, and measuring it well means comparing you with you.
Your trend.
Not the average →
A transition is measured against where you started, not against everyone else your age.
What the evidence actually says.
Perimenopause is staged by changes in cycle pattern, not by a blood level, because FSH and oestradiol swing from week to week.
Sleep disruption, slower recall and mood changes can begin while periods are still fairly regular and blood tests still look normal.
At the start of the transition the rate of fat gain doubles and lean mass begins to fall, without any change in the rate of weight gain.
LDL cholesterol, ApoB and bone loss all change most around the final period, and none of them can be felt.
AMH predicts the timing of the final period better than FSH, and every other marker is most useful read against your own earlier results.
Frequently asked.
Can a blood test tell me if I’m in perimenopause?
Usually not on its own. FSH and oestradiol swing widely from week to week during perimenopause, so a single result can look normal. The transition is identified mainly by changes in cycle length alongside symptoms, and AMH can help estimate how far along you are.
Why are my hormone levels normal when I feel so different?
Because a blood test captures one day. Early in the transition oestradiol can run high one week and low the next, and symptoms such as broken sleep tend to follow those swings, which a single sample misses.
When does perimenopause usually start?
Most often in the mid-to-late forties, and it can last several years before the final period. Symptoms such as night sweats, poor sleep and changes in memory can begin while cycles are still fairly regular.
What should be monitored during perimenopause?
A record of cycles and symptoms, plus lipids and ApoB, fasting insulin, iron studies, thyroid function and a baseline bone density. These are most useful repeated over time and compared with your own earlier results.
Your transition, measured.
A structured protocol built on comprehensive testing, then measured year on year. Telehealth, Australia-wide.
Book a discovery callReferences.
- Santoro N. Perimenopause: from research to practice. J Womens Health (Larchmt). 2016;25(4):332-339. doi.org/10.1089/jwh.2015.5556
- Freeman EW, Sammel MD, Lin H, Nelson DB. Associations of hormones and menopausal status with depressed mood in women with no history of depression. Arch Gen Psychiatry. 2006;63(4):375-382. doi.org/10.1001/archpsyc.63.4.375
- Harlow SD, Gass M, Hall JE, et al. Executive summary of the Stages of Reproductive Aging Workshop + 10: addressing the unfinished agenda of staging reproductive aging. Menopause. 2012;19(4):387-395. doi.org/10.1097/gme.0b013e31824d8f40
- Hale GE, Zhao X, Hughes CL, et al. Endocrine features of menstrual cycles in middle and late reproductive age and the menopausal transition classified according to the Staging of Reproductive Aging Workshop (STRAW) staging system. J Clin Endocrinol Metab. 2007;92(8):3060-3067. doi.org/10.1210/jc.2007-0066
- Kravitz HM, Zhao X, Bromberger JT, et al. Sleep disturbance during the menopausal transition in a multi-ethnic community sample of women. Sleep. 2008;31(7):979-990. PMID 18652093
- Avis NE, Crawford SL, Greendale G, et al. Duration of menopausal vasomotor symptoms over the menopause transition. JAMA Intern Med. 2015;175(4):531-539. doi.org/10.1001/jamainternmed.2014.8063
- Greendale GA, Huang MH, Wight RG, et al. Effects of the menopause transition and hormone use on cognitive performance in midlife women. Neurology. 2009;72(21):1850-1857. doi.org/10.1212/WNL.0b013e3181a71193
- Greendale GA, Sternfeld B, Huang M, et al. Changes in body composition and weight during the menopause transition. JCI Insight. 2019;4(5):e124865. doi.org/10.1172/jci.insight.124865
- Matthews KA, Crawford SL, Chae CU, et al. Are changes in cardiovascular disease risk factors in midlife women due to chronological aging or to the menopausal transition? J Am Coll Cardiol. 2009;54(25):2366-2373. doi.org/10.1016/j.jacc.2009.10.009
- Greendale GA, Sowers M, Han W, et al. Bone mineral density loss in relation to the final menstrual period in a multiethnic cohort: results from the Study of Women’s Health Across the Nation (SWAN). J Bone Miner Res. 2012;27(1):111-118. doi.org/10.1002/jbmr.534
- Finkelstein JS, Lee H, Karlamangla A, et al. Antimullerian hormone and impending menopause in late reproductive age: the Study of Women’s Health Across the Nation. J Clin Endocrinol Metab. 2020;105(4):e1862-e1871. doi.org/10.1210/clinem/dgz283
