Blood Tests For Hair Loss. What To Test And Why It Matters

‍ ‍

Hair loss has many drivers, and several of the most common are invisible on the scalp because they live in your blood rather than your follicles. Low iron stores, an underactive or overactive thyroid, low vitamin D, B12 or zinc, and hormonal imbalances can all cause or worsen shedding and thinning, and none of them respond to PRP, minoxidil or any scalp treatment, because the problem is not in the follicle at all. Testing before treating is the difference between fixing the cause and paying to treat around it, which is why a blood-test-first approach matters. This is what to test, what each result reveals, and why the order matters.

‍ ‍

Key points

‍ ‍

Several common drivers of hair loss, including low ferritin and iron stores, thyroid dysfunction, and low vitamin D, B12 or zinc, are invisible on the scalp and show only in blood, and because the problem is a deficiency or imbalance rather than the follicle, they do not respond to PRP or topical treatment, so treating without testing wastes time and money. The standard panel covers ferritin and iron stores, full thyroid function, vitamin D, B12, key hormones, HbA1c and zinc, and both NICE and the British Association of Dermatologists stress identifying the underlying cause before treating hair loss, which begins with the right blood work.

‍ ‍

Want your hair loss tested properly first? Message a GMC-registered doctor on WhatsApp or email team@thewellnesslondon.com.

‍ ‍

Why blood tests matter in hair loss

‍ ‍

Because a large share of hair loss is either caused or made worse by something measurable in blood, and none of it improves until that is corrected. A woman losing handfuls in the shower may have low iron stores rather than a hair problem at all. A person whose hair has thinned diffusely over a year may have an undiagnosed thyroid condition. Someone recovering from illness, surgery or a period of poor eating may be low in several nutrients at once. In each case the scalp looks like the problem, but the cause is elsewhere, and only a blood test finds it.

‍ ‍

This is why testing first is not a formality but the single most useful step. Treating the follicle while ignoring a correctable deficiency is like watering a plant in exhausted soil, the effort goes in and nothing changes. As our doctors put it, "the commonest reason hair treatment fails is that nobody checked what was feeding the hair in the first place." Correcting a deficiency is often cheaper, simpler and more effective than any injection, and knowing that before you spend on treatment is the point.

‍ ‍

What we test, and what each result reveals

‍ ‍

This is a general guide to the standard hair loss panel and why each part is on it, though your exact tests depend on your history and examination. Ferritin and iron stores come first, because low iron is a very common and correctable driver of shedding, particularly in women. Full thyroid function is checked because an underactive or overactive thyroid causes diffuse thinning and is easily missed. Vitamin D is included because low levels are associated with several types of hair loss and are common in the UK, and B12 because deficiency, more common in vegetarians, vegans and after certain surgery, affects hair. Zinc is a less common but genuine contributor to shedding when low. Key hormones are read for the patterns relevant to female and male pattern loss and to conditions such as PCOS, and HbA1c screens for the blood sugar problems that can accompany hormonal hair loss. The value of the panel is that it catches the invisible contributors in one visit, so treatment starts from a corrected baseline rather than a guess.

‍ ‍

Not sure what is driving yours? Ask our doctors on WhatsApp.

‍ ‍

When a deficiency is the whole story, and when it is only part

‍ ‍

Sometimes correcting a deficiency is all that is needed. A person with heavy shedding and very low ferritin will often see the shedding settle once iron stores are rebuilt over a few months, with no other treatment required, and being told that, rather than being sold a course of injections, is exactly what an honest assessment should deliver.

‍ ‍

More often a deficiency is one part of a bigger picture. Someone with genetic pattern loss can also have low iron and an underactive thyroid layered on top, and in that situation the pattern loss still needs treating, but it will respond far better once the contributors are corrected first. This is why the blood work and the scalp examination are read together rather than separately. The blood tells you what is holding hair back, and the dermoscopy tells you whether the follicles are miniaturising, still viable, or gone, and only the two together produce a plan that works.

‍ ‍

Why testing before treating saves money

‍ ‍

Because the alternative is paying to treat around a problem you have not found. A course of PRP or a year of topical treatment costs far more than a blood panel, and if the real driver was a correctable deficiency the whole time, that spend was largely wasted. Testing first means you either correct something cheaply and avoid unnecessary treatment, or you go into treatment from a corrected baseline where it has the best possible chance of working. Either outcome is better than guessing.

‍ ‍

What happens when you enquire

‍ ‍

Every enquiry begins with a free doctor-led suitability review rather than a booking. A GMC-registered doctor takes your history, examines your scalp with dermoscopy, and arranges the blood tests relevant to your case, covering ferritin and iron stores, full thyroid function, vitamin D, B12, key hormones, HbA1c and zinc, run from the same clinic.

‍ ‍

You then get one of two answers, both useful. Either you are approved for treatment, with a plan that starts from a corrected baseline and realistic expectations for three, six and twelve months, or you are not, in which case we say so plainly. Frequently that means a deficiency to correct and nothing more, or a temporary shed that will recover on its own. We decline a meaningful share of enquiries on exactly those grounds, because treating a follicle while ignoring what starves it helps nobody.

‍ ‍

For context on cost, flagship Harley Street and Mayfair clinics commonly charge £600 to £850 or more per PRP session. Our care is doctor-led and priced below those rates, confirmed after your free review, and a good number of people who contact us are told a correction is all they need.

‍ ‍

Why people choose The London PRP Clinic by The Wellness

‍ ‍

We are doctor-led and blood-test-first, with every treatment performed by GMC-registered doctors, and no clinician treats a patient here until they have completed 100 supervised treatments. Diagnosis, testing and the full regenerative range sit under one roof, so the recommendation follows your blood work and your scalp rather than a product line.

‍ ‍

Across our work we report an 87 percent patient success rate, a 32 percent average density increase in hair restoration and more than 187 five-star reviews. We also train other clinicians through our Academy.

‍ ‍

Book your free suitability review. Message us on WhatsApp, email team@thewellnesslondon.com, or call +44 20 3951 3429.

‍ ‍

Frequently asked questions about blood tests for hair loss

‍ ‍

What blood tests should I have for hair loss?

‍ ‍

A standard panel covers ferritin and iron stores, full thyroid function, vitamin D, B12, key hormones, HbA1c and zinc, because these are the common measurable drivers of shedding and thinning. Your exact tests depend on your history.

‍ ‍

Can low iron cause hair loss?

‍ ‍

Yes. Low ferritin and iron stores are a common and correctable cause of shedding, particularly in women, and the shedding often settles once stores are rebuilt over a few months.

‍ ‍

Can a thyroid problem cause hair loss?

‍ ‍

Yes. Both an underactive and an overactive thyroid can cause diffuse thinning, and because it is easily missed, thyroid function is part of the standard hair loss panel.

‍ ‍

Will correcting a deficiency regrow my hair?

‍ ‍

Where a deficiency is the main driver, correcting it often allows shedding to settle and hair to recover. Where pattern loss is also present, the deficiency should still be corrected first so treatment works better.

‍ ‍

Do I need blood tests before PRP?

‍ ‍

We test first because several drivers of hair loss are invisible on the scalp and do not respond to PRP. Starting from a corrected baseline gives any treatment the best chance of working.

‍ ‍

Is it worth testing if my hair loss is clearly genetic?

‍ ‍

Yes, because correctable deficiencies frequently sit on top of genetic loss and hold treatment back. Correcting them first improves the response to treatment.

‍ ‍

This article is for information and does not replace personal medical advice. All treatments at The London PRP Clinic by The Wellness are performed by GMC-registered doctors. Individual results vary. Reviewed by the medical team at The London PRP Clinic by The Wellness. Last updated August 2026.

<!-- JSON-LD SCHEMA. Paste into Squarespace page header code injection --> <script type="application/ld+json"> </script>