The word 'menopause' gets used as if it's a door you walk through in your mid-fifties. Biologically, it's the end of a ten-year process - and the ten years before the door are where most of the decisions that matter get made.
Perimenopause is defined retrospectively. You're in it when you have cycle-length changes, and you're out of it 12 months after your last period. The problem is that cycle-length changes can be the last symptom to show up. Bone loss, LDL drift, anxiety, insomnia, and joint pain can all precede that final cycle change by five to ten years.
The biological timeline
Late 30s - stealth onset
The first hormone to change can be progesterone. Anovulatory cycles can start creeping in. On paper, everything can look fine. Symptomatically, sleep can become lighter, PMS can get sharper, anxiety can climb the week before periods.
Early 40s - estradiol turbulence
Estradiol may not gradually decline (Burger et al., 2008). It can swing. Individual months can hit peri-pregnancy levels and then crash. This is when hot flashes, headaches, and memory lapses can begin. FSH can start drifting up but the numbers can bounce - a single normal FSH may mean nothing in this phase (Burger, 2011).
Mid to late 40s - FSH can commit
FSH can rise consistently (Hale et al., 2007). Estradiol can trend down. Cycles can shorten first (21–24 days) before they lengthen and eventually stop. Bone density loss can accelerate (Finkelstein et al., 2008). LDL-C and ApoB can start climbing even without dietary change.
The menopause transition is when HRT works best
The 2022 NAMS position statement reaffirms that hormone therapy started within 10 years of the final period carries a favourable risk-benefit profile for most women. Initiating outside that window tips the balance.
What to track
- Estradiol and progesterone at day 3 and day 21 - once a year through your 40s.
- FSH trend (not one-shot) every 12–18 months.
- TSH + Free T3 annually; thyroid disease can surface in perimenopause.
- ApoB and hs-CRP annually from 40 onward.
- DEXA at 45 if you have risk factors, otherwise at 50.
What 'normal' actually means
Lab reference ranges are built on mixed populations. A perimenopausal woman in the upper third of 'normal' FSH may be in a very different place than a 25-year-old in the same range. Your EllaDx report shows the lab's own range, with plain-language context.
References
- Burger, H. G., et al. (2008). Cycle and hormone changes during perimenopause: the key role of ovarian function. Menopause, 15(4 Pt 1), 603-612. PMID 18574431
- Burger, H. G. (2011). Unpredictable endocrinology of the menopause transition: clinical, diagnostic and management implications. Menopause International, 17(4), 153-154. PMID 22120939
- Hale, G. E., et al. (2007). 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. Journal of Clinical Endocrinology & Metabolism, 92(8), 3060-3067. PMID 17550960
- Finkelstein, J. S., et al. (2008). Bone mineral density changes during the menopause transition in a multiethnic cohort of women. Journal of Clinical Endocrinology & Metabolism, 93(3), 861-868. PMID 18160467
