FSH Test and Perimenopause: What Your Results Actually Mean
Understand what the FSH test measures, why doctors order it during perimenopause, what your results mean, and what to do next.
What Is FSH and What Does the Test Measure?
FSH stands for follicle-stimulating hormone. Your pituitary gland releases it to signal your ovaries to develop and release eggs. As perimenopause progresses, your ovaries become less responsive, so the pituitary pumps out more FSH in an effort to compensate. A blood test can measure how much FSH is circulating. A high reading suggests your ovaries are under hormonal pressure, which aligns with perimenopause.
Why FSH Matters During Perimenopause
Rising FSH is one of the biological hallmarks of the menopause transition. When FSH climbs above roughly 10 IU/L on a consistent basis, it signals that ovarian reserve is declining. For women in their 40s with irregular periods, fatigue, and hot flashes, an elevated FSH confirms that hormone fluctuation is likely driving those symptoms. This gives both you and your doctor a clearer picture of what is happening in your body.
What Changes to Expect in Your FSH Levels
FSH does not rise in a straight line. Early perimenopause brings erratic swings, so a single normal result does not rule out perimenopause. You might test on a day when FSH looks typical, then test a week later and see a significantly higher number. By late perimenopause and into menopause, FSH generally stays elevated above 25 to 30 IU/L. Your doctor may want more than one test to build a reliable picture.
How to Get Tested
Ask your GP for a blood test that includes FSH, LH (luteinising hormone), and sometimes oestradiol. Ideally the test is done on days two to five of your menstrual cycle when baseline readings are most informative. If your periods are very irregular or have stopped, timing matters less. The test is a simple blood draw and results are usually available within a few days.
Understanding Your Results
A reading below 10 IU/L is generally considered normal for a reproductive-age woman. Levels between 10 and 20 IU/L suggest early ovarian change. Levels above 25 IU/L consistently indicate significant perimenopause or menopause. However, FSH alone is not a diagnosis. Symptoms, menstrual history, and sometimes other hormone levels all contribute to a full clinical picture. One elevated result is not the whole story.
What to Do With Your Results
If your FSH is elevated and your symptoms are affecting daily life, talk with your doctor about management options. These include HRT, lifestyle changes, and addressing specific symptoms. Tracking your symptoms over time helps you and your doctor spot patterns alongside the numbers. Logging how you feel day to day means you walk into appointments with evidence, not just impressions.
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