Perimenopause library · Foundations

Hormones during the transition — and why one lab result is not a diagnosis

Updated 2026-08-24 · 2 min read

Ovarian follicle depletion drives the transition. Reviews of the hormone sequence (Su and Freeman, 2009) describe a typical order: anti-Müllerian hormone (AMH) falls first, inhibin B falls, follicle-stimulating hormone (FSH) rises, and estradiol is often maintained — sometimes even transiently high — before it drops in late transition.

That last point surprises people who expect estrogen to be “low” the whole time. Daily sampling in the 1990s already showed that perimenopausal cycles can produce more estrogen, not only less, than mid-reproductive cycles.

SWAN data on AMH and inhibin B (Sowers and colleagues, 2008) found that log-AMH decline marked a point about five years before the final menstrual period. Many AMH values were already too low to measure precisely by then, and that low state still tracked with time to the final period. Inhibin B also fell four to five years before, but was a weaker marker.

STRAW+10 treated AMH and antral follicle count as promising, not yet standardized enough in 2011 to be primary staging criteria. The practical conclusion in the reviews has not changed for an individual visit: there are no validated hormone cutpoints that diagnose the menopausal transition or predict the final menstrual period for one person. Diagnosis, when a clinician makes one, is clinical — bleeding pattern plus symptoms — not a single FSH or AMH number.

Hormone levels also vary with body mass, smoking, and race/ethnicity in SWAN and Penn data. A result that looks “high” or “low” on a printout is still not a personal forecast.

ClearDay will not interpret your labs. If you already have results, take the paper (or the portal screenshot) to the person who ordered them.

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