Ferritin is the protein that stores iron in your body. It is not the same as serum iron — which measures iron currently circulating in your blood — but it is a much better indicator of your iron reserves. When ferritin is low, your body is running short of stored iron, even if your haemoglobin and serum iron still look normal.
UK reference ranges for ferritin
Reference ranges for ferritin vary between UK laboratories, but the following are typical:
| Group | Typical reference range | Notes |
|---|---|---|
| Women (non-pregnant) | 13–150 µg/L | Wide range; symptoms often appear below 30 µg/L |
| Men | 30–400 µg/L | Higher stores typical; low ferritin less common |
| Pregnant women | Varies; lower threshold often applied | Iron requirements increase significantly in pregnancy |
What low ferritin feels like
Low ferritin can cause symptoms even before haemoglobin drops and anaemia develops. This is sometimes called iron deficiency without anaemia, and it is underdiagnosed. Common symptoms include:
- Persistent fatigue, even after adequate sleep
- Hair thinning or increased shedding (telogen effluvium)
- Difficulty concentrating or brain fog
- Restless legs, particularly at night
- Breathlessness on exertion
- Cold hands and feet
- Brittle nails
What causes low ferritin?
The most common causes of low ferritin in UK patients are:
- Inadequate dietary iron — particularly in those following plant-based diets, as non-haem iron from plants is less bioavailable than haem iron from meat
- Menstrual blood loss — heavy periods are the most common cause of low ferritin in women of reproductive age
- Malabsorption — conditions such as coeliac disease, Crohn's disease, and atrophic gastritis impair iron absorption
- Increased demand — pregnancy, intense endurance exercise, and growth spurts in adolescents all increase iron requirements
- Chronic blood loss — gastrointestinal bleeding (from ulcers, polyps, or other causes) can deplete iron stores gradually
What counts as a good ferritin level?
The NHS reference range sets the floor, not the target. Many haematologists and functional medicine practitioners consider ferritin below 30 µg/L to be functionally low in symptomatic patients, and some recommend aiming for 50–100 µg/L for optimal wellbeing. However, the right target depends on your individual circumstances, symptoms, and any underlying conditions.
Can ferritin be too high?
Yes. Elevated ferritin (above 200 µg/L in women, above 300 µg/L in men) can indicate iron overload (haemochromatosis), chronic inflammation, liver disease, or other conditions. Ferritin is an acute phase reactant — it rises during infection or inflammation even when iron stores are normal. A high ferritin result always warrants investigation.
What to ask your GP
- What is my ferritin level, and how does it compare to my previous tests?
- Should I have a full iron panel (serum iron, TIBC, transferrin saturation) as well?
- Is my ferritin low enough to explain my symptoms?
- If supplementation is appropriate, what dose and form do you recommend?
- Should we investigate the cause of low ferritin, particularly if it is recurring?
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