Best Perimenopause Blood Tests to Ask For in the UK
Which blood tests actually matter in perimenopause? A guide to FSH, oestradiol, thyroid, ferritin, vitamin D, and more, with UK-specific advice.
Why Blood Tests in Perimenopause Are Complicated
Many women go to their GP expecting a single blood test to confirm perimenopause and come away disappointed. The reality is that perimenopause is a clinical diagnosis based on symptoms and age, not a lab value. Hormone levels fluctuate so much during this transition that a single result can be misleading. That said, blood tests are still valuable for ruling out other conditions with similar symptoms, identifying deficiencies that are making things worse, and giving you a baseline before starting or adjusting treatment.
FSH and LH: What They Do and Do Not Tell You
Follicle-stimulating hormone (FSH) is the test most commonly associated with menopause. When the ovaries are producing less oestrogen, the pituitary gland releases more FSH to try to stimulate them. A raised FSH (above 30 IU/L on two tests taken six weeks apart) in a woman over 45 with symptoms is supportive of perimenopause, but it is not definitive. FSH can fluctuate month to month in perimenopause, meaning one normal result does not rule it out. Luteinising hormone (LH) tells a similar story. If you are on hormonal contraception, these tests are not useful at all. NICE guidelines in the UK state that women over 45 with typical symptoms do not need blood tests at all for a perimenopause diagnosis.
Oestradiol: Useful but Limited
Oestradiol is the main form of oestrogen measured in blood. The problem is that levels in perimenopause swing widely depending on where you are in your cycle, the time of day, and stress levels. A single low result is consistent with perimenopause but not conclusive. A single normal result does not rule it out. Oestradiol testing is more useful for monitoring during HRT to check whether your dose is working, rather than for diagnosis. If you are on HRT and still experiencing symptoms, your GP or menopause specialist may test oestradiol to assess whether your dose needs adjustment.
Thyroid Panel: TSH, Free T4, and Free T3
Thyroid conditions are more common in women and become more common with age. Hypothyroidism and perimenopause share many symptoms including fatigue, brain fog, weight gain, mood changes, and disturbed sleep. A standard NHS thyroid test checks TSH only. If TSH is normal but you still feel unwell, ask for free T4 and free T3 as well. Some women have normal TSH but suboptimal conversion of T4 to the active T3. Thyroid antibodies (anti-TPO) are worth requesting if there is a family history of thyroid disease, as Hashimoto's thyroiditis can progress slowly over years before TSH changes.
The Tests Most Worth Asking For
A full blood count identifies anaemia, which causes fatigue, poor concentration, and breathlessness. Ferritin (stored iron) should be tested separately because serum iron and haemoglobin can be normal while ferritin is low, which still causes symptoms. Vitamin D levels in the UK are frequently low, especially through winter and spring. Target levels above 75 nmol/L for bone health. B12 deficiency is more common after 40 and causes neurological symptoms easily confused with perimenopause brain fog. HbA1c gives a three-month average of blood sugar and is worth having baseline data on given that insulin resistance increases after 40. Testosterone is not routinely offered on the NHS but is important if you are experiencing low libido, fatigue, or reduced motivation.
Private Testing Options in the UK
If your GP declines certain tests or you want results faster, private blood testing is accessible and relatively affordable in the UK. Medichecks and Thriva both offer comprehensive perimenopause panels that cover all the key markers including oestradiol, FSH, thyroid, ferritin, vitamin D, and B12. Results come back within a few days and include commentary. The Newson Health clinic and other menopause specialists also offer full panels as part of consultations. For testosterone, private testing is often the most practical route since NHS thresholds may not reflect optimal female levels. Keep copies of all results so you can track changes over time and share with different clinicians.
Making Your Results Actionable
Getting blood tests is only useful if you know what to do with the results. Many women find the reference ranges confusing because they are often very wide, and a result that is technically normal may still be suboptimal. Write down your symptoms before your appointment and be specific about severity and frequency. If you are logging symptoms in an app like PeriPlan, you can show a clinician actual patterns over weeks rather than trying to summarise from memory. This context makes it much easier to interpret lab results alongside your real experience. Ask for a copy of every test result and keep them in one place so you can compare over time.
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