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Most missed — most easily fixed

Ferritin — the test your doctor probably skipped

Exhausted. Hair falling out. Brain fog. Cold constantly. Your doctor runs bloods and says everything is normal. But there is a very good chance your ferritin — the iron storage protein that builds your red blood cells, neurotransmitters, and hormones — is nowhere near optimal. And the lab has not told you.

Rose
Rose
"I sat in a doctor's office with a ferritin of 16 and was told my iron was fine. I was losing handfuls of hair, exhausted by midday, and could not string a sentence together. When I finally pushed for the number and looked it up myself, I understood immediately. That gap — between 'technically not deficient' and 'actually functioning' — is where so many women are living. This page exists because no one told me."
The gap nobody explains
Lab says normal above 12
Optimal: 70–100
Standard lab range (above 12 = "normal") Optimal for symptom-free function (70–100)
Standard lab range says
Above 12 ng/mL
Set to identify frank iron deficiency anaemia. Survival level — not the level at which you feel well, think clearly, or grow healthy hair.
Optimal for menopausal women
70–100 ng/mL
The level associated with normal energy, hair growth, cognitive function, and mood — supported by clinical research and specialist consensus.
What low ferritin actually does to you
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Exhaustion that sleep does not fix
Ferritin is required to make haemoglobin — the protein that carries oxygen in red blood cells. When ferritin is low, oxygen delivery to every cell in the body is impaired. The result is a deep, unresponsive fatigue that feels different from ordinary tiredness. It does not lift after a good night's sleep because the problem is not sleep — it is oxygen.
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Hair shedding and thinning
Iron is a required cofactor for the enzyme ribonucleotide reductase, which drives cell division in hair follicles. Hair follicles are among the most metabolically active structures in the body — among the first to be affected when ferritin falls. Research consistently shows that ferritin below 70 ng/mL is associated with hair shedding, and that correcting ferritin above 70 produces measurable regrowth within 3-6 months.
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Brain fog and poor concentration
Iron is essential for the synthesis of dopamine, serotonin, and noradrenaline — all three neurotransmitters. It is also required for myelin production (the insulation around nerve fibres). Low ferritin produces cognitive symptoms that are clinically indistinguishable from perimenopausal brain fog — word retrieval difficulty, working memory impairment, slow processing. Both problems often coexist, stacking on each other.
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Cold all the time
Thyroid hormone production requires iron — specifically, thyroid peroxidase, the enzyme that makes thyroid hormones, is an iron-containing enzyme. Low ferritin impairs thyroid function even when TSH appears normal. It also reduces the metabolic heat generation that depends on oxygen delivery. Cold intolerance, cold hands and feet, and difficulty warming up are classic low ferritin symptoms.
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Breathlessness and palpitations
When oxygen-carrying capacity falls, the heart compensates by beating faster — producing palpitations and breathlessness on mild exertion. Many women in perimenopause notice palpitations and assume it is hormonal (which it also can be). Low ferritin is an easily correctable additional cause that should always be investigated.
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Low mood and anxiety
The link between iron and mood is direct: dopamine and serotonin synthesis both require iron. A woman with ferritin of 15 is making less serotonin and less dopamine than she would with ferritin of 80. This is not a mood disorder. It is iron deficiency presenting as depression and anxiety — and it responds to iron, not antidepressants.
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Restless legs at night
Restless legs syndrome is strongly associated with low ferritin — specifically ferritin below 75 µg/L. The mechanism is dopamine pathway disruption in the brain circuits that control motor activity during sleep. RLS guidelines specifically recommend targeting ferritin above 75 µg/L as a first-line intervention, before pharmaceutical treatment.
Why perimenopausal women are especially at risk
Heavy periods deplete iron faster than most diets replace it
The flooding and irregular heavy periods of perimenopause — which affect up to 40% of women in the transition — can deplete iron stores significantly faster than a normal diet replaces them. A woman losing 80ml+ per period (flooding counts as above 60ml) can lose enough iron in a single cycle to reduce her ferritin by 5-10 points. Over six months of heavy cycles, this compounds to significant depletion — even in women who eat red meat regularly. The solution is not just eating more iron — it is supplementing adequately to outpace the loss.
The symptoms stack on menopause — and nobody separates them
Fatigue, brain fog, hair thinning, low mood, cold intolerance — every single low ferritin symptom is also a menopause symptom. Most doctors (and most women) attribute everything to hormones. Low ferritin gets missed because nobody looks for it when everything can be explained by perimenopause. The two problems compound each other and compound the suffering. A ferritin test is cheap, easy, and will frequently reveal a second treatable cause sitting underneath the hormonal picture.
How to fix it
1
Get the number
Ask for ferritin specifically. Not FBC, not haemoglobin — ferritin. And ask for the actual number, not "it's normal." A number is information. "Normal" is not.
2
Know where you are
Below 30: significantly depleted. 30-70: suboptimal — common range where symptoms are present but standard tests show "normal." 70-100: optimal. Above 100: fine, no supplementation needed for iron status. Use the lab reference ranges tool on Rose to check your result.
3
Choose the right iron supplement
Iron bisglycinate (also called iron glycinate or ferrous bisglycinate) is the form with the best absorption and fewest side effects. Ferrous sulfate — the standard prescribed form — is poorly tolerated by most women (constipation, nausea). Bisglycinate is gentler and more bioavailable. 25-50mg elemental iron daily is the typical dose for repletion.
4
Take it correctly
With vitamin C (200-500mg) — dramatically increases absorption. Separate from coffee, tea, dairy, and calcium by at least 2 hours. Separate from levothyroxine (thyroid medication) by 4 hours minimum — iron blocks thyroid hormone absorption. On an empty stomach if tolerated, with food if not.
5
Retest at 3 months
Ferritin rises slowly — typically 1-2 ng/mL per week with consistent supplementation. Three months of consistent supplementation should produce a meaningful rise. Retest, see where you are, and discuss whether to continue, adjust dose, or investigate further if ferritin is not rising as expected.
6
Find the cause
Low ferritin has a reason. The most common in perimenopausal women: heavy periods (address with HRT or tranexamic acid), poor absorption (coeliac disease — ask for a coeliac screen), vegetarian or vegan diet (plant iron is less bioavailable), or a combination. Treating the cause prevents needing to supplement indefinitely.
What to say to your doctor — word for word

These scripts are written for the five most common situations. Use the one that matches where you are.

1
Requesting the test
What to say
"I would like my ferritin tested specifically — not just a full blood count or haemoglobin. I understand ferritin is the storage form of iron and is the most sensitive marker of iron status. Can I have the actual number, not just whether it is in or out of range?"
Why this works: GPs often run a full blood count (FBC) which checks haemoglobin. Haemoglobin only falls when iron deficiency is severe — you can be functionally iron-depleted for years before haemoglobin falls. Ferritin falls first. You need ferritin specifically.
2
When told your result is "normal"
What to say
"Thank you — can you tell me the actual number? I understand the standard lab range flags ferritin as low only below 12, but research and clinical guidelines for hair health and energy suggest the optimal level for symptom-free function is above 70 ng/mL. My result of [X] is within the standard range but below the optimal level I have read about. Can we discuss supplementation?"
Why this works: The lab normal range (above 12 ng/mL) was set to identify frank iron deficiency anaemia — not to identify the level at which you feel well. A ferritin of 18 is technically normal. A ferritin of 18 with the symptoms above is undertreated iron deficiency.
3
When told you don't need iron supplements
What to say
"I appreciate that I am not anaemic. But I am experiencing significant fatigue, hair shedding, and brain fog that are consistent with suboptimal ferritin. I would like to trial iron supplementation — specifically iron bisglycinate, which is well tolerated — and retest my ferritin in 3 months to see if it rises above 70. Can we discuss this?"
Why this works: Iron bisglycinate is significantly better tolerated than ferrous sulfate (less constipation, nausea) and has equivalent or better absorption. Taken with vitamin C, separate from coffee, tea, calcium, and thyroid medication.
4
When asking why ferritin is low
What to say
"Can we discuss why my ferritin might be low? I would like to understand whether heavy perimenopausal periods are depleting my iron stores, whether I have any absorption issues (I understand coeliac disease and low stomach acid can impair iron absorption), and whether my diet is contributing."
Why this works: Low ferritin has a cause. The most common in perimenopausal women: heavy periods (flooding, clots, periods lasting more than 7 days), poor dietary iron intake, and absorption problems. Finding the cause means treating it properly rather than just supplementing indefinitely.
5
Asking about the full iron panel
What to say
"In addition to ferritin, can I have a full iron panel — including serum iron, TIBC (total iron binding capacity), and transferrin saturation? Together these give a complete picture of my iron status that ferritin alone cannot provide."
Why this works: Ferritin can be elevated by inflammation even when iron stores are actually low (ferritin is an acute phase reactant). A full panel distinguishes true iron depletion from inflammatory ferritin elevation.
If your doctor won't test or won't take the level seriously
Private ferritin testing is available for £20-40 at Medichecks, Thriva, Bluecrest, and similar private labs. You do not need a GP referral. A home fingerprick blood test will give you a ferritin number within a few days. You can then bring the result to your GP or discuss it with a private doctor. You should not have to go private for this — but you can.
Rose on this
"The ferritin conversation is the one that makes me most frustrated — because it is so simple, so cheap to test, and so fixable. And yet women spend years being told their bloods are normal while they are living with ferritin of 15 and wondering why they feel like they are falling apart. Ask for the number. Look at the number. Know what it means. This is one of the few things in perimenopause where an answer is genuinely simple."
Check your result now
Lab reference ranges tool — enter your ferritin and see where you stand › Full lab guide — every biomarker explained › Upload your blood panel to Rose › Doctor conversation guides — more exact language › Restless legs syndrome — ferritin above 75 is the first intervention › Hair thinning at menopause — ferritin is the most common missed cause ›
Written by
Rose
Rose
Navigating perimenopause · Researcher · Founded rosemyfriend.com
Research basis
PubMed · Cochrane reviews · NICE guidelines · British Menopause Society · The Menopause Society
Read methodology →
Last updated
April 2026
Key sources
Rushton DH et al. — Ferritin and female hair loss (Clin Exp Dermatol, 2002)Trost LB et al. — The diagnosis and treatment of iron deficiency and its potential relationship to hair loss (J Am Acad Dermatol, 2006)Earley CJ et al. — Brain iron in the restless legs syndrome (Sleep Med, 2014)Camaschella C — Iron-deficiency anaemia (N Engl J Med, 2015)Soppi ET — Iron deficiency without anaemia (Clin Case Rep, 2018)
Rose provides evidence-graded educational information — not medical advice. Always discuss health decisions with a qualified healthcare provider. Full disclaimer · About Rose