Timing hypothesis
What it means
The timing hypothesis is the idea that when a woman starts hormone therapy, relative to her menopause, strongly affects whether the benefits outweigh the risks.
Understanding timing helps you and your prescriber think through whether and when hormone therapy might support bone protection as you go through menopause.
After the Women's Health Initiative study raised concerns about hormone therapy, researchers took a closer look and realized that age matters a great deal. This rethinking is called the timing hypothesis. The idea is that the same treatment can look very different depending on when a woman starts it relative to menopause.
For women who start hormone therapy before age 60, or within about ten years of their final period, and who have no specific contraindications, the evidence generally looks favourable, with symptom relief and bone protection, and no extra cardiovascular harm seen in that group. Starting much later in life, when arterial disease may already be present, is where most of the cardiovascular concerns from the original study came from.
The way hormones are delivered also matters. Transdermal oestrogen, like a patch or gel, skips first-pass processing by the liver and appears to carry a lower risk of blood clots than oral oestrogen in observational data. Women with a uterus also need a progestogen to protect the uterine lining, and the specific type used may influence breast risk differently. Any decision about starting, changing, or stopping hormone therapy belongs with your prescriber, who can weigh your personal history and timing.
How sure is this?
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.
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.
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.
Read the full answer →Related words
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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.
