Blood Tests for Hair Loss: Which Ones Help

Noticing more hair in your brush, on your pillow or in the shower drain can be worrying. Hair loss has many causes. Some types, such as male and female pattern hair loss, are long term and run in families. Others are temporary and linked to illness, stress, weight loss, a new medicine or a shortage of iron. A common pattern called telogen effluvium can start around 3 months after a trigger such as illness, childbirth or a stressful event.

Blood tests cannot diagnose the type of hair loss you have, but they can check for treatable causes that doctors commonly look for, such as low iron stores and thyroid problems. This guide explains which blood tests are most useful for hair loss, which test to start with, what blood tests cannot tell you and when to see a GP.

Test it in Chiswick: our Vitamins and Minerals Check blood test costs £99, with your result explained in person by a practitioner. No GP referral needed. Book this test or call 020 4515 0000.

Quick answer

The most useful blood tests for hair loss are ferritin (your iron stores) and thyroid function (TSH, with free T4), as iron deficiency and thyroid conditions are the causes doctors most often check for. Many people add vitamin D, vitamin B12 and zinc, and a full blood count to look for anaemia. Women with irregular periods, acne or extra facial or body hair may also benefit from a testosterone and free androgen index test to look for signs of polycystic ovary syndrome. A normal set of results is still useful: it helps rule out common treatable causes.

Blood tests that can help

Ferritin and iron studies

Ferritin shows how much iron your body has stored. The NHS lists hair loss, noticing more hair coming out when brushing or washing it, as a symptom of iron deficiency anaemia, and iron deficiency is one of the temporary causes of hair loss named by the NHS. Iron stores can run low before haemoglobin falls, so ferritin is often the first test to check. Our Ferritin test (£49) is the simplest option, and the Iron Status Check (£59) adds serum iron, transferrin and transferrin saturation for a fuller picture. Read more in our guide to ferritin levels explained.

Thyroid function: TSH and free T4

Both an underactive and an overactive thyroid can affect hair. The NHS lists dry hair or hair loss among the symptoms of an underactive thyroid, alongside tiredness, feeling cold and weight gain. A TSH test (£39) is a good screen, and our Thyroid panel (£59) adds free T3, free T4 and thyroid antibodies, which can show whether the immune system is affecting the thyroid. See our guide to thyroid function test results.

Vitamin D

Studies have found lower vitamin D levels in people with some types of hair loss, particularly alopecia areata (patchy hair loss). However, research has not shown that low vitamin D causes hair loss, or that supplements help unless you are actually low. A Vitamin D test (£59) tells you whether your level is worth correcting. Our vitamin D levels guide explains the result bands.

Vitamin B12

Low vitamin B12 is not one of the main recognised causes of hair loss, but it is often checked alongside ferritin because a deficiency can cause anaemia and tiredness, and it is more likely if you eat a vegan diet or have a condition that affects absorption. A Vitamin B12 test (£49) is quick to add. Read vitamin B12 levels explained.

Zinc

Zinc is needed for healthy hair growth, and hair loss is a recognised sign of zinc deficiency. True deficiency is uncommon in people who eat a varied diet, but it is more likely with gut conditions, after weight loss surgery, with a vegetarian or vegan diet, or with heavy alcohol use. Blood zinc levels can also dip during an infection, so a single low result is best interpreted with a practitioner. Our Zinc test (£79) measures it on its own.

Female androgens and polycystic ovary syndrome

Higher levels of androgens (hormones such as testosterone) can contribute to female pattern hair loss. The NHS lists hair loss and excess hair growth among the symptoms of polycystic ovary syndrome, which the NHS now also calls polyendocrine metabolic ovarian syndrome (PMOS). If you also have irregular periods, acne or unwanted facial or body hair, a Free Androgen Index test (£69) measures testosterone and SHBG together. The Hormone Health Check (£69) adds LH, FSH, oestradiol, progesterone and prolactin. Our guide to testosterone levels in women explains the results.

Full blood count

A Full Blood Count (£59) measures haemoglobin and the size of your red blood cells. It shows whether you have anaemia and gives clues to its cause, for example small red cells with iron deficiency or large red cells with low B12 or folate.

Which test should I book?

• A focused start: Iron Status Check, £59. Ferritin, serum iron, transferrin and transferrin saturation, ideal if iron is your main concern.
• A broader picture: Thyroid, £59. TSH, free T3, free T4 and thyroid antibodies, to check the thyroid side of hair loss.
• The fullest view: Vitamins and Minerals Check, £99. Ferritin and iron studies, vitamin D, vitamin B12, folate, zinc, magnesium and calcium in one sample. It does not include thyroid tests, so many people add a TSH test.

If you would like iron, thyroid, vitamin D, B12 and a full blood count in a single panel, our Tired All The Time (£159) covers all of these, although it does not include zinc.

What blood tests cannot tell you

Most hair loss is diagnosed by looking at the pattern of hair loss and the scalp, not by a blood test. Male and female pattern hair loss usually have normal blood results, and the British Association of Dermatologists notes that female pattern hair loss is usually diagnosed from a history of gradual thinning. Telogen effluvium after illness, surgery, childbirth or stress often settles on its own, and in around 1 in 3 people no cause is found. Scalp conditions, tight hairstyles, some medicines and stopping hormone treatment can also play a part. If your results are normal, a GP or dermatologist can examine your scalp and discuss other causes.

If you take a hair, skin and nails supplement, tell us before your test. Many contain biotin, which can affect some blood test results, including thyroid tests. We will advise you whether to pause it first.

When to see a GP urgently

Hair loss on its own is rarely an emergency, but the NHS advises seeing a GP if:

• your hair loss is sudden
• you develop bald patches
• you are losing hair in clumps
• your scalp itches or burns
• you are worried about your hair loss

See a GP promptly if hair loss comes with unexplained weight loss, extreme tiredness, a racing heart or changes to your periods. Call 999 if you have chest pain that spreads to your arm, neck, jaw or back, or chest pain with breathlessness, sweating or feeling sick. If you feel very unwell and are not sure what to do, call NHS 111.

Frequently asked questions

Which blood test is best for hair loss?

Ferritin and thyroid function are the two tests doctors most often check first. A panel such as the Vitamins and Minerals Check covers ferritin, vitamin D, B12 and zinc together, and a TSH test can be added for the thyroid.

Can low ferritin cause hair loss?

Yes, iron deficiency is a recognised cause of temporary hair loss, and the NHS lists hair loss as a symptom of iron deficiency anaemia. If your ferritin is low, your GP or practitioner can look for the reason, for example heavy periods or diet, and discuss treatment.

Which blood tests should women ask for with hair thinning?

Ferritin, thyroid function, vitamin D and a full blood count are a sensible start. If you also have irregular periods, acne or excess hair growth, add a testosterone and free androgen index test. Hair thinning can also be a symptom of the perimenopause and menopause.

Can thyroid problems cause hair loss?

Yes. The NHS lists dry hair or hair loss as a symptom of an underactive thyroid. Hair often improves once thyroid levels are treated, although regrowth can take several months.

Do I need to fast before a hair loss blood test?

Fasting is not usually needed for these tests. We will tell you when you book if your chosen panel has any special instructions, and you should mention any supplements, especially biotin.

Hair loss blood tests in Chiswick

Omnia Lifestyle is at 8 to 9 Bedford Corner, The Avenue, Chiswick, London W4 1LZ, a short walk from Turnham Green station (District line; Piccadilly line trains stop there early morning and late evening only) and served by buses 94, E3 and 272. Limited parking is available on request when you book. Every clinic test price includes your sample taken at the clinic, analysis at the Randox accredited laboratory, a practitioner review of your result with you, and a GP feedback report on request. You do not need a GP referral, and most results are back within a few working days.

Useful links: start with our Vitamins and Minerals Check or the Iron Status Check, add a Thyroid panel, browse all women's health blood tests, or compare every blood test and price. You may also find our guides to ferritin levels and testosterone levels in women helpful.

This article is general information, not medical advice. Discuss your results with your GP or practitioner.