Why "Normal" Isn't Good Enough: What Your Blood Tests Aren't Telling You About Your Hair Loss
Why "Normal" Isn't Good Enough: What Your Blood Tests Aren't Telling You About Your Hair Loss
By Deborah Maguire, Registered Trichologist
You've been told your bloods are normal. So why is your hair still falling out?
It's one of the most common things I hear in clinic. A woman sits across from me, frustrated and exhausted, and tells me she's already been to her GP. She's had blood tests. Everything came back normal.
And yet her hair is still falling out.
Here's what I tell her, and what I want you to know too.
Normal and optimal are not the same thing.
How blood test ranges actually work
When your GP looks at your blood results, they're comparing your levels against a reference range. That range is calculated from a large population of people, and it tells your doctor whether you fall within what's considered medically acceptable.
But medically acceptable means what keeps you functioning. What keeps you out of a clinical deficiency. What keeps you alive.
It does not mean what helps you thrive. And it certainly doesn't mean what your hair needs to grow.
The ranges are deliberately wide. Someone at the very bottom of "normal" and someone at the very top will get the same result on paper: normal. But their bodies,and their hair, can be experiencing something very different.
The levels that matter most for hair loss…
In my trichology practice, I see the same deficiencies come up time and time again in women who are shedding. These aren't “maybe’s” These are direct, documented causes of hair loss.. and they're routinely missed because a woman's levels fall just inside the normal range.
Ferritin (stored iron…. This is like a warehouse for your iron )… and the blood test reveals your “stable” iron levels.
This is the one I see most often. Ferritin is the protein that stores iron in your body, and it's absolutely critical for healthy hair growth. Hair follicles are some of the most metabolically active cells in the body - they need iron to function.
The NHS normal range for ferritin typically ranges at 10-20 micrograms per litre. But in my clinical experience, women need ferritin levels of at least 70 micrograms per litre-and ideally closer to 100 - for optimal hair growth.
A woman with ferritin above 15 will be told she's normal. Her hair will disagree.
Serum Iron
( this can fluctuate)
NHS range is 10-30 umol/L whereas I’d prefer to see it at 18-26
Serum iron is rarely used alone for diagnosis because it fluctuates throughout the day based on your recent meals.
Vitamin D
We are chronically low in Vitamin D in the UK. It's not a lifestyle failure ..it's a geography problem. And Vitamin D deficiency has a well-established link to hair shedding, particularly the type that affects the hair cycle directly.
Standard ranges consider anything above 50 nmol/L to be sufficient. But for hair health, we're looking for levels closer to 100 nmol/L or above. Again, the gap between "sufficient" and "optimal" is significant - and your hair feels it.
B12
Vitamin B12 is essential for red blood cell production, which means it's essential for getting oxygen and nutrients to your hair follicles. Low B12 , even low-normal B12, can slow hair growth and increase shedding.
This one is particularly common in women who eat less meat, follow plant-based diets, or have digestive issues that affect nutrient absorption. And it's one that's frequently overlooked because the numbers sit just inside the acceptable range.
NHS Ranges: 250-1000
( which has significantly increased in the last 10 years it was 110 -1000)
Optimal is 500-800
Although it's uncommon, vitamin B12 or folate deficiency (with or without anaemia) can lead to complications, particularly if you have been deficient in vitamin B12 or folate for some time.
Potential complications can include:
-problems with the nervous system
-temporary infertility.
-heart conditions
-pregnancy complications and birth defects
Thyroid function
Thyroid issues are a major cause of hair loss in women, and they are notoriously under-diagnosed. Standard thyroid tests measure TSH (thyroid stimulating hormone) and T4 but often don't include the full picture of T3
Free T4 is the primary storage hormone produced directly by your thyroid gland.
NHS Range: 10.0 - 22.0 pmol/L
The Optimum Target: 15.0 to 19.0 pmol/L.
The Hair Risk:
If your FT4 sits at the bottom of the normal range (e.g., 10.5 pmol/L), your body may prioritize vital organs like the heart over non-essential functions, ( such as hair growth ) slowing down the active growth phase of your hair follicles.
Optimum Free T3
Free T3 is the active hormone that your body converts from T4. This is the fuel that your hair follicles actually absorb to trigger growth
Standard NHS Range: 3.1 - 6.8 pmol/L.
The Optimum Target: 5.0 to 6.2 pmol/L.
The Hair Risk:
Some women have plenty of storage hormone (T4) but lack the enzymatic ability to convert it efficiently into active hormone (T3). If your FT3 (free T3)drops below 4.5 pmol/L, cellular metabolism drops, which can push hair follicles into a resting stage all at once, sparking diffuse shedding.
A woman can have suboptimal thyroid function and still be told everything looks fine.
If you have hair loss alongside fatigue, feeling cold, weight changes or low mood, push for a full thyroid panel not just TSH.
(it’s frustrating that not all NHS GP practices test for T3… in which case you may have to have a private test if you feel you need this.
Why this gap exists? and why it isn't your GP's fault…
I want to be clear about something. This isn't about blaming GPs. They are working within a system, with guidelines built for population-level medicine. They are not trained in trichology. The connection between low-normal nutrient levels and hair loss is simply not part of standard medical training.
The gap is real. It's systemic. And it means that thousands of women every year are told they're fine when their hair is telling them something very different.
Knowing this gap exists is the first step to closing it.
What you can do
Ask for the actual numbers. Don't accept "normal" as an answer. Always always give your GP feedback , all to often in my practice. A client may be prescribed medication by a consultant for thyroid or hormones by her GP or even antidepressants and when I ask did it change anything to improve your hair did it make you feel better? whenever they said “no”I asked them if they’d reported back to the GP with this and they actually hadn’t, GP’s do need to know if your symptoms have improved or not.
If you don’t use the NHS digital app for your blood test results you can ask your GP or a private practitioner to email your results.
Ask for your specific ferritin, Vitamin D, B12 and thyroid levels.. Then look at where they sit within the range, not just whether they pass or fail.
Push for a full thyroid panel.
If thyroid issues are suspected, ask for T3 and T4 to be tested alongside TSH.
Consider seeing a trichologist. A registered trichologist can review your blood results in the context of your hair loss specifically something a GP won't have the time or training to do.
Address nutritional gaps properly.
If your levels are low-normal, supplementing with the right ingredients at the right levels can make a real difference. This is exactly why I formulated Seed & Soul ™️ Nutrition For Hair., because I was tired of watching women fall through the gap between normal and optimal, with nothing designed specifically to meet them there.
The bottom line
Your hair is not lying to you. If it's falling out, something is driving that and low-normal nutrient levels are one of the most common causes I see in clinic. But if you felt your hair loss could be due to immense stress and ask for a cortisol level blood test.
You deserve more than a number that sits inside a range. You deserve to understand what optimal looks like for your body, and to have the tools to get there.
Don't stop looking for answers. The answers exist.
Deborah Maguire is a registered trichologist and co-founder of Seed & Soul, a pharmaceutical-grade hair and scalp supplement formulated for women experiencing hair loss. Seed & Soul is as seen in British Vogue, SheerLuxe and Woman & Home.
If you're ready to start addressing your hair loss from the inside out, find out more at seedandsoul.co
This blog is for informational purposes and does not constitute medical advice