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Your ferritin level is probably normal. It is probably not high enough for your hair.
Iron deficiency is the most common nutritional cause of hair loss worldwide — affecting nearly 1 in 3 women of reproductive age. Most of them have been told their iron is normal. It is. But "normal" and "sufficient for hair growth" are two different numbers that most standard blood panels will never flag.
A ferritin of 25 ng/mL is "normal" on most lab reference ranges. Hair follicles require ferritin above 70 ng/mL to maintain a healthy growth cycle. The distance between those two numbers is where most nutritional hair loss lives — and where most blood panels will never look.
There is a number on your blood test that your doctor probably considers normal. It is probably not high enough for your hair.
Ferritin — the protein that stores iron in the body — is measured routinely in standard blood panels. The reference range most laboratories use to define "normal" ferritin is based on the threshold below which iron-deficiency anaemia develops. For women, that lower bound is typically 12 to 20 nanograms per millilitre. You are told your iron is fine. The hair continues to thin.
The problem is that the threshold at which hair follicles are sufficiently supplied with iron is not the same as the threshold at which anaemia is diagnosed. Most trichologists and dermatologists specialising in hair loss recommend maintaining ferritin above 50 to 70 ng/mL for optimal hair health — a target that the standard lab normal range does not reach, and that a routine blood panel will never flag as deficient.
Iron deficiency is the most common nutritional cause of hair loss worldwide, affecting nearly 1 in 3 women of reproductive age. A serum ferritin level below 30 ng/mL is strongly associated with increased hair shedding even when haemoglobin remains in the normal range. The hair loss is real. The anaemia test is clear. And the gap between those two facts is where most nutritional hair loss lives — undetected, untreated, and frequently attributed to stress, genetics, or ageing.
The Gap
Why "normal" iron and "sufficient for hair" are different numbers.
Hair follicles rank among the most metabolically active tissues in the human body — they divide faster than almost any other cell type and require continuous, robust nutrient delivery to maintain the growth cycle. Iron is central to this: it is required for the activity of ribonucleotide reductase, the enzyme that produces the DNA building blocks needed for rapid cell division. When iron stores fall below the threshold the hair matrix needs, the follicle responds by shortening the anagen phase and transitioning to telogen — shedding prematurely to conserve resources for more critical biological functions.
This happens well before anaemia develops. The body prioritises haemoglobin production — keeping red blood cells oxygenated is a survival imperative. Iron is diverted from storage (ferritin) to haemoglobin long before haemoglobin levels drop. By the time your haemoglobin is low enough to flag as anaemia, your ferritin has been depleted for months — and so has the iron supply to your follicles.
The standard lab normal for ferritin is typically 12–20 ng/mL for women — the anaemia prevention threshold. The hair health threshold used by most specialist trichologists is 50–70 ng/mL.
This means a woman with ferritin of 25 ng/mL is told her iron is normal. She is not anaemic. But her ferritin is less than half the level at which hair follicles function optimally. She has been iron-deficient for hair health purposes for months, possibly years, while every blood test has returned "within normal range."
I'm guessing here on specific optimal ranges — go verify with your own clinician, as these thresholds are not universally agreed upon. But the directional point is consistent across the specialist literature: the anaemia threshold and the hair health threshold are different numbers.
Who Is Most at Risk
The populations the standard panel consistently misses.
Monthly iron loss through menstruation is the primary reason iron deficiency disproportionately affects women of reproductive age. Heavy menstrual bleeding compounds the depletion significantly. 10 to 20% of menstruating women have iron deficiency, and 3 to 5% are frankly anaemic. The gap between those two numbers — the 15-17% who are iron deficient but not anaemic — is the population whose hair loss is consistently attributed to other causes.
Pregnancy dramatically depletes iron stores — the foetus draws iron from maternal reserves throughout gestation. Delivery involves blood loss. Breastfeeding continues the demand. Postpartum hair loss — telogen effluvium beginning two to four months after delivery — is driven partly by the hormonal shift of delivery and partly by the iron depletion that preceded it. The hair loss attributed to "postpartum hormones" frequently has a ferritin component that is never tested.
Non-haem iron — found in plant foods — is absorbed at roughly one third the rate of haem iron from animal sources. Vitamin C enhances absorption; calcium, coffee, and tea inhibit it. Someone eating a plant-based diet without deliberate iron optimisation and pairing strategy can have a diet that appears iron-rich by quantity while being iron-poor by bioavailability. The hair is frequently the first tissue to show the depletion.
The emerging GLP-1/semaglutide nutritional depletion angle affects millions of patients in 2026. Rapid weight loss on GLP-1 medications reduces total food intake, frequently reducing iron, zinc, and protein below the threshold hair follicles need. The telogen effluvium that follows rapid weight loss — typically beginning two to four months after the loss begins — is partly hormonal and partly nutritional depletion driven by reduced intake.
The Testing Problem
What to ask for — and what the numbers actually mean.
A specialist evaluation interprets ferritin against the 50 to 70 ng/mL hair health threshold rather than the standard lab normal range. Most GP appointments do not. The complete iron assessment for hair loss purposes requires more than a standard ferritin test:
The Biotin Warning
The supplement that may be hiding your deficiency.
Biotin lab interference is a genuine patient safety issue. High-dose biotin supplementation — common in hair growth supplements — interferes with immunoassay-based laboratory tests, including thyroid panels and ferritin tests in some assay formats. A woman taking high-dose biotin who gets a ferritin test may receive a falsely elevated result — told her iron stores are adequate when they are not.
If you are taking a hair supplement containing biotin and you are getting blood tests to investigate hair loss, stop the biotin for at least 48 to 72 hours before the blood draw. This is not widely known outside specialist practice and is almost never flagged at the GP level. It has been producing false-negative results in hair loss investigations for years.
The honest framework for nutritional hair loss.
Iron deficiency is the most common nutritional driver of hair loss. It is routinely missed because the standard blood panel uses an anaemia threshold rather than a hair health threshold. It is fully reversible in most cases — iron deficiency hair loss is fully reversible once ferritin levels are restored to 70 ng/mL or above, with visible regrowth typically starting within 3 to 6 months.
The most important thing you can do if you suspect nutritional hair loss is get the right test, interpreted against the right threshold, by someone who understands the difference between the anaemia cutoff and the hair health target. Then address the deficiency through food first — iron-rich foods paired with vitamin C, avoiding the absorption inhibitors — and supplementation when diet is insufficient.
The daily botanical ritual does not treat iron deficiency. But it creates the circulatory environment — improved scalp blood flow through ginger, rosemary, and massage — that delivers whatever iron is in circulation more efficiently to the follicles that need it. The nutrition addresses the supply. The ritual improves the delivery.
Know your number. Then work toward the right one.
The ritual that supports optimal delivery.
Ginger, rosemary, and the daily scalp massage improve blood flow to the follicle — delivering whatever nutrients the bloodstream carries more effectively to the follicles that depend on them.
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