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Bone Health Glossary · Hormones

Hormone replacement therapy

Also called: HRT, hormone therapy

Evidence
◆ Strong Clinical Evidence
Topic
Hormones
Taught in
Tier 2 · Lesson 9
In plain English

What it means

Hormone replacement therapy (HRT) replaces oestrogen, often with a progestin, after menopause and has been shown to reduce fractures while it's being taken.

Why it matters for your bones

Oestrogen loss at menopause speeds up bone breakdown, and HRT is one of the clearest evidence-backed ways to reduce that fracture risk while it's being used.

Hormone replacement therapy (HRT) is treatment with oestrogen, often with a progestin, given to replace hormones that drop sharply at menopause. Research going back to the Women's Health Initiative trial shows it reliably reduces fractures, including hip fractures, in postmenopausal women — the clearest and least disputed finding from that study, even though the trial became known for other reasons. The decision to start, stop, or change HRT always belongs to you and your prescriber, who can weigh it against your personal history.

HRT works by telling your skeleton to stop breaking down bone so fast — it restores a more protective hormonal environment. But it doesn't supply the mechanical signal that tells bone where to build; that comes from loading. The two address different problems, which is why they're often described as working together rather than as substitutes for each other.

An honest limitation: bone density gained during HRT is largely lost in the years after stopping, and fracture protection fades with it, so it's something you maintain rather than something that banks permanent bone. There's also no credible evidence that supplements or over-the-counter products replicate what hormone therapy does for bone, so claims of 'natural HRT' are worth treating with suspicion. If you're near menopause or in a higher-risk group — early menopause, androgen deprivation therapy, aromatase inhibitors, long-term steroid use — the window to have this conversation with a prescriber matters, so it's worth not putting off.

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Evidence

How sure is this?

The research behind this
Strong Clinical Evidence

Graded Strong Clinical Evidence: Supported by multiple well-designed clinical studies in humans. Read each study with its grade in mind. One study is a piece of the picture, not the whole of it.

3 peer-reviewed studies, free with an Academy login
✦ The aha

HRT is one of the clearest evidence-backed ways to reduce fracture risk while you're taking it.

Your next step

Where this leads

185 discoveries so far
Question

Wondering why your doctor seems cautious about this option despite the evidence? This explains where that caution comes from and how understanding has shifted.

Should I be on hormone therapy for my bones — and why did my doctor seem so cautious about it?
Take me there Strong Clinical Evidence
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Where the Academy teaches it

This page is the short version. The lessons teach it in full, with the context around it and a quiz to lock it in.

Quick answers

Questions people ask about this

Whether hormone therapy is right for your bones is a decision only you and your prescriber can make, based on your personal history — but it's worth knowing the evidence on hormones and bone is actually strong and has often been misrepresented, which is likely why your doctor is being careful. The caution usually traces back to one 2002 trial that was widely misreported; since then, the understanding has shifted considerably, especially around a woman's age and timing when therapy starts.

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Related words

Estrogen
Established Science

Estrogen is a hormone that protects bone by keeping bone-removing cells in check. Falling estrogen, especially at…

Menopause
Established Science

Menopause is when your periods stop and estrogen levels drop sharply, which speeds up bone loss because the cells…

Women's Health Initiative
Strong Clinical Evidence

The Women's Health Initiative, or WHI, was a major 2002 study on hormone therapy in postmenopausal women that found…

Timing hypothesis
Strong Clinical Evidence

The timing hypothesis is the idea that when a woman starts hormone therapy, relative to her menopause, strongly…

Bioidentical hormones
Established Science

Bioidentical (or body-identical) hormones are hormones that are structurally identical to the ones your own body…

Premature menopause
Strong Clinical Evidence

Premature menopause is when periods stop before about age 45, due to primary ovarian insufficiency, ovary removal,…

Turner syndrome
Standard Definition

Turner syndrome is a genetic condition in girls and women caused by a missing or incomplete X chromosome. It often…

Perimenopause
Standard Definition

Perimenopause is the hormonal transition phase leading up to menopause, when estrogen levels fluctuate and periods…

Education only, not medical advice. Decisions about tests, medications and treatment belong with your own doctor. OsteoStrong does not diagnose, treat or cure any disease.

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