Hair loss: which blood values can play a role?

Not all hair loss shows up in your blood

The most common form of hair loss is hereditary: gradually thinning hair in a fixed pattern, in men the temples and crown, in women mainly the parting. This form cannot be seen in blood.

There is also telogen effluvium: two to three months after a significant trigger, such as childbirth, surgery, high fever, a crash diet or a stressful period, a striking amount of hair suddenly falls out. This usually recovers by itself, although it can take months.

A blood test is most worthwhile with diffusely thinning hair without a clear pattern or obvious trigger. Then you want to know whether one of these causes is holding the hair back:

• an iron deficiency
• a thyroid problem
• a shortage of zinc or vitamin D
• a hormonal shift

These are all causes that are measurable and that you or your doctor can subsequently act on. Measuring also prevents you from piling up supplements at random without knowing whether they are needed.

Ferritin and iron: the best-known link

Hair follicles are among the fastest-dividing cells in the body, which makes them sensitive to low iron stores. Ferritin, the storage form of iron, is then the value to know: it falls earlier than haemoglobin, which means hair loss can occur before there is any anaemia.

Women with heavy periods run the greatest risk. One caveat: ferritin rises with inflammation, so a reassuring result does not always rule out a deficiency. Our doctors therefore assess the value in your context.

If low stores are found, the follow-up question is why: heavy periods, a diet low in iron, reduced absorption or a combination of these.

Do not correct a deficiency on your own with high doses of iron; too much iron has downsides as well, and the right dose and duration matter. The result is the starting point for that: with an abnormal value, the report tells you what a common next step is, and when consulting your GP is sensible.

Thyroid: both underactive and overactive

Both an underactive and an overactive thyroid can cause diffuse hair loss. There are usually other signals as well: with an underactive thyroid tiredness, feeling cold and weight gain, with an overactive one restlessness, palpitations and weight loss. TSH is the first value to measure, usually together with free T4.

Good to know: even once the thyroid is properly regulated again, hair needs time. Recovery is a matter of months rather than weeks. If you are unsure whether your complaints fit the thyroid, measuring is easier than continuing to wonder: one tube of blood clarifies the first step.

Zinc and vitamin D

Zinc is involved in the production of keratin, the building material of hair. A deficiency is not common with a varied diet, but occurs more often with plant-based eating, bowel conditions and prolonged intensive training. You can have zinc measured as an individual test for €74 all-in.

Vitamin D has receptors in the hair follicle and low values are common in the Netherlands, especially at the end of winter; this test costs €69 all-in.

Let us be honest here: taking extra on top of what you need does not make hair grow faster. Supplementation is only worthwhile if there genuinely is a deficiency. If you already take a multivitamin, mention it; our doctors take it into account when assessing your value.

Hormones in women

In women, the hormonal side deserves attention when hair loss coincides with childbirth, the menopause, stopping or switching the pill, or an irregular cycle. With PCOS, too, the balance between female and male hormones can affect the hair.

The Women's Hormones package maps the most important female hormones in a single blood draw for €159, plus a €29 collection fee (free above €225). You will find the full composition on the product page; the results are reviewed and explained by a doctor. Always discuss an abnormal result in the context of your complaints; a hormone value on its own rarely tells the whole story.

What you may expect from the results: an explanation or an exclusion, not a miracle cure. If a deficiency or a thyroid abnormality is found, that is actually good news, because something can be done about it. Do count on patience afterwards: a hair follicle moves through slow cycles, and visible recovery typically takes three to six months.

How to approach it practically

A few practical choices make the result more useful:

1. 1If you want several values measured, combine them in a single blood draw; that saves needles and gives the reviewing doctor a more complete picture.
2. 2Ideally test before you start taking supplements, otherwise you are mainly measuring the supplement.
3. 3For hormone tests the day of your cycle can matter; the product page tells you what to take into account.
4. 4Take a photo of your parting or hairline on the day of the draw.

Hair loss progresses so gradually that a comparison over three months says more than your day-to-day impression, and that way you can genuinely see whether an approach is working.

Hair loss is visible and tangible, and that is exactly what makes it unpleasant to keep living with. A single blood draw shows whether a measurable cause is playing a part, so you can act on it instead of gambling with supplements. And if the blood turns out to be fine, you know the cause lies elsewhere and you can move forward with a GP or dermatologist in a targeted way.