You stand in the shower and see another clump of hair between your fingers. In your brush, on your pillow, in the drain: it feels as if it does not stop. Maybe your ponytail has thinned or you see more scalp through your parting. For many women this feels like a quiet loss, and it often runs deeper than a cosmetic worry.
Here is what I often tell women: hair loss is rarely random. Your hair is one of the first places your body cuts back when something is off with your iron stores, your thyroid or your hormone balance. A blood test turns guesswork into concrete direction, although the result always remains a snapshot that a doctor reads in your context.
Below you will read which hormonal and nutrition-related causes most often play a part, which blood values can give insight, and when testing is worthwhile.
When is hair loss more than normal?
Everyone loses hair daily, on average around 50 to 100, as part of the natural growth cycle. If you structurally lose more, see patches forming or notice your hair thinning, an underlying cause may be at play. In women, hormonal shifts and nutritional deficiencies are the most common explanations.
The tricky part is that the cause often becomes visible with a delay. Stress, a strict diet, a delivery or a change in your contraception may have been the trigger two to four months earlier. According to Thuisarts.nl, diffuse hair loss after such an event is usually temporary and the hair often recovers on its own. Still, a test helps to rule out an underlying deficiency or thyroid problem.
Which blood value fits which pattern?
Not every form of hair loss points the same way. The pattern, diffuse or rather around the crown, and the accompanying symptoms often give a hint. The table below links a recognisable picture to the value that usually says the most about it. It is a tool to prepare your conversation with the GP, not a diagnosis.
| Pattern or accompanying symptom | Value that can give insight | What it may point to |
|---|---|---|
| Diffuse thinning, tired, pale, heavy periods | Ferritin, iron, transferrin saturation | A low iron store as a common cause |
| Dry, brittle hair, feeling cold, weight gain, tired | TSH, free T4 | A possibly underactive thyroid |
| Thinning around crown and parting, sometimes acne or excess hair | Testosterone, DHEA-S | An androgen pattern, sometimes fitting PCOS |
| Began around menopause, after the pill or after pregnancy | Estradiol, progesterone | A hormonal shift that shortens the growth phase |
| Thin, brittle hair, vegetarian diet or much sport | Zinc | A possible zinc deficiency disrupting the growth cycle |
Ferritin: the most underestimated cause
Ferritin reflects your iron stores and is one of the most common causes of hair loss in women, one that is regularly overlooked. Your haemoglobin can still be normal while your ferritin has already dropped considerably, because the hair is one of the first places your body cuts back when the store shrinks.
Especially if you menstruate, eat vegetarian or do a lot of sport, it can be worthwhile to have your ferritin checked. Women with heavy periods are at extra risk, because they lose more iron each month than average. If you want to understand your whole iron status, also have your iron and transferrin saturation measured alongside ferritin. The Iron Status brings these values into view in one draw. Which ferritin value is desirable for you is something you discuss with your GP, as it can differ per situation.
Thyroid hormones: the silent disruptor
Your thyroid regulates your metabolism and directly influences the hair growth cycle. Both an underactive and an overactive thyroid can cause hair loss. Thyroid conditions are more common in women than in men.
With an underactive thyroid the hair often becomes dry, brittle and thin, and the loss is diffuse across the whole scalp. You may also notice your eyebrows thinning, especially the outer part, alongside fatigue, weight gain and feeling cold. With an overactive thyroid the hair can become finer and limper, often with nervousness, weight loss and palpitations.
The main marker is TSH, which drives your thyroid and is the first indicator of an abnormality. If TSH is abnormal, it is valuable to also measure free T4. The Thyroid Complete brings these values into view together. For more background, read our overview on thyroid symptoms in women.
Estrogen and progesterone: hormonal shifts
During periods of major hormonal change, such as menopause, after stopping the pill or after pregnancy, hair loss can occur. Estrogen has a protective effect on hair growth: when it falls, the growth phase shortens and more hairs enter the shedding phase at once.
Estradiol (E2) is the main estrogen to measure. A fall, combined with low progesterone, can contribute to diffuse hair loss, especially in perimenopause or after stopping hormonal contraception.
After pregnancy hair loss is almost universal. During pregnancy high estrogen levels keep the hair in the growth phase, and after delivery those levels fall, causing many hairs to shed at once. The Dutch Society of Obstetrics and Gynaecology (NVOG) describes this postpartum hair loss as a normal, usually temporary change that mostly begins two to four months after delivery. Stopping the pill can produce something similar, as your body adapts to your own hormone production.
Testosterone and DHEA-S: androgen pattern
Androgenetic alopecia, sometimes called hormonal baldness, also occurs in women. It shows differently than in men: the hair thins around the crown and the parting widens, while the hairline usually stays intact. This form relates to a sensitivity to androgens, male sex hormones that women also produce in small amounts.
- Testosterone: an elevated total testosterone can point to PCOS or another cause of androgenisation. This pattern can also occur with normal testosterone.
- DHEA-S: this adrenal hormone can be elevated with adrenal-related androgen production and is more stable than testosterone.
Important: this pattern can also occur with normal androgen levels, because the hair follicle itself is sensitive to the androgens. In that case the blood values are normal, but the hair still responds. If you suspect PCOS, it is worthwhile to also look at the ratio between LH and FSH alongside testosterone and DHEA-S. The Women's Hormones panel measures these sex hormones in one draw.
Zinc: the forgotten mineral
Zinc plays a role in cell division and protein production, two processes that are important for hair growth. A zinc deficiency can disrupt the hair growth cycle and lead to thin, brittle hair. Zinc is also involved in the production of keratin, the protein that your hair largely consists of.
Zinc deficiency is more common than you think, especially in women who eat vegetarian or vegan, do a lot of sport or experience long-term stress. Good sources of zinc are beef, pumpkin seeds, cashews and legumes. If you want to know whether your zinc level is adequate, a blood test can give insight into that.
When is testing worthwhile?
Not every period of some extra hair loss is cause for concern, and seasonal shedding in autumn, for example, is normal. In the following situations it can be worthwhile to have your blood tested:
- You structurally lose more than 100 hairs a day and it lasts longer than six weeks
- You see patchy bald spots, which may require other diagnostics
- Your hair becomes visibly thinner at the parting or crown
- The hair loss goes together with fatigue, weight change or cycle changes
- The loss began after stopping the pill, a pregnancy or around menopause
The sooner you have a possible cause in view, the more targeted you can look at next steps together with your GP. With patchy bald spots a condition like alopecia areata may play a part, which should always be assessed by a doctor.
What can you do yourself alongside testing?
While you wait for your results you can already pay attention to your hair health. According to the Health Council of the Netherlands (Gezondheidsraad), a varied diet is part of the foundation of your health, and that also touches your hair.
- Eat varied with enough protein, iron and zinc
- Avoid strict dieting; your hair needs a stable supply of nutrients
- Limit heat styling and tight hairstyles that pull on the hair roots
- Work on stress reduction, as long-term stress can disrupt hair growth via cortisol
Frequently asked questions
Can stress cause hair loss?
Yes, it can. Long-term or severe stress can lead to telogen effluvium, a form of diffuse hair loss that begins two to four months after a stressful period. This type is usually temporary; once your body recovers, hair growth usually resumes within six to twelve months.
How quickly do you see improvement?
That depends on the cause. With an iron deficiency you may see improvement after several months, and with thyroid issues once the values are back in balance. Hair grows on average about a centimetre a month, so patience helps. Often you first notice less hair shedding, and only afterwards do you see new hair growing.
Which test is most informative for hair loss?
There is no single test that covers everything. A commonly used combination is ferritin, TSH, estradiol, testosterone and zinc, with which you bring the most common causes into view. Which test fits you is best discussed with your GP.
Sources
- Thuisarts.nl. I have hair loss. Dutch College of General Practitioners. Available via thuisarts.nl.
- NHG Guideline Thyroid disorders. Dutch College of General Practitioners. Available via richtlijnen.nhg.org.
- Dutch Society of Obstetrics and Gynaecology (NVOG). Patient information on the period after delivery. Available via degynaecoloog.nl.
- Health Council of the Netherlands (Gezondheidsraad). Nutrition norms and varied diet. Available via gezondheidsraad.nl.
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