What Ferritin Levels Mean
Ferritin is a protein that stores iron inside your cells and releases it in a controlled way when the body needs it. A serum ferritin test measures the amount circulating in your blood — giving clinicians an indirect estimate of total iron stores. But ferritin is also an acute-phase reactant, which means inflammation, infection, and liver disease can push the value up independently of iron status. Understanding this nuance is key to reading your result correctly.
What ferritin actually measures
Most of the iron in your body is stored inside cells bound to a protein called ferritin. A small amount of ferritin leaks into the bloodstream, and this is what the serum ferritin test detects. In people without significant inflammation or liver disease, serum ferritin correlates reasonably well with total body iron stores — a low ferritin almost always indicates depleted stores, while a high ferritin may indicate iron overload (though this requires confirmation with other tests).
Ferritin is not the same as serum iron, transferrin, or haemoglobin. Each measures a different aspect of iron metabolism:
| Test | What it measures | Affected by inflammation? |
|---|---|---|
| Serum ferritin | Indirect estimate of iron stores in cells | Yes — rises with inflammation |
| Serum iron | Iron currently circulating in blood | Yes — falls with inflammation |
| Transferrin / TIBC | The protein that carries iron; TIBC reflects capacity to carry more | Yes — transferrin falls with inflammation |
| Transferrin saturation (TSAT) | Percentage of transferrin currently bound to iron | Partly — affected by both iron status and inflammation |
| Haemoglobin (Hgb) | Iron-containing protein in red blood cells that carries oxygen | Indirectly (severe anaemia of chronic disease) |
| MCV / MCH | Size and haemoglobin content of red blood cells | Not directly — but iron deficiency eventually produces small, pale cells |
Ferritin reference ranges — what the numbers say
Reference intervals vary between laboratories and are often stratified by sex. The following are representative ranges used by many labs, but always use the range printed on your own report:
| Group | Typical reference interval | Notes |
|---|---|---|
| Adult men | 24–336 ng/mL (µg/L) | Ranges vary; some labs use 15–300 ng/mL |
| Adult women (premenopausal) | 11–307 ng/mL | Lower end common due to menstrual losses; some labs cut off at 150 |
| Adult women (postmenopausal) | Often similar to men's range | Confirm with your lab's specific values |
| Children (varies by age) | Ranges differ significantly by age group | Use age-specific paediatric reference intervals |
An important clinical caveat: some guidelines and clinicians consider ferritin below 30 ng/mL (or even 50 ng/mL) as suggestive of iron deficiency even when the value falls within the laboratory's reference interval. This is because the lower portion of the "normal" range may reflect near-depleted stores in some individuals, particularly those with symptoms such as fatigue or restless legs. Discuss with your clinician what threshold is appropriate for your situation.
What a low ferritin result means
A ferritin below the reference interval reliably indicates that iron stores are depleted. This is the most specific finding in iron deficiency — a low ferritin almost always means there is insufficient stored iron, even before haemoglobin drops or red blood cells become abnormally small.
Iron depletion develops in stages. In the earliest stage, iron stores fall but haemoglobin and red cell indices remain normal — this stage is detected only by low ferritin. As depletion progresses, transferrin saturation falls and serum iron decreases. In established iron deficiency anaemia, haemoglobin is low and red cells become small (low MCV) and pale (low MCH). Ferritin remains low throughout.
Common reasons for low ferritin include:
- Dietary insufficiency — inadequate intake of iron-rich foods (particularly haem iron from meat). Vegetarian and vegan diets provide non-haem iron, which is less readily absorbed.
- Increased demand — pregnancy substantially increases iron requirements. Growing children and adolescents also have higher demands.
- Menstrual blood loss — heavy periods are one of the most common causes of iron deficiency in premenopausal women.
- Gastrointestinal blood loss — ulcers, gastritis, colorectal polyps or cancer, and coeliac disease can all cause ongoing occult blood loss that depletes iron. New iron deficiency in postmenopausal women or in men should prompt investigation to rule out GI causes.
- Malabsorption — coeliac disease, inflammatory bowel disease, and gastric bypass surgery reduce iron absorption.
- Frequent blood donation — regular donors can deplete stores over time without adequate dietary compensation.
Symptoms that may accompany low ferritin include fatigue, reduced exercise tolerance, poor concentration, pallor, cold intolerance, brittle nails, hair loss, and — in some people — restless leg syndrome. However, symptoms correlate imperfectly with ferritin levels, and some people with significantly low ferritin have few noticeable symptoms.
What a high ferritin result means
An elevated ferritin is more complex to interpret than a low ferritin because ferritin is an acute-phase reactant — it rises as part of the body's inflammatory response, independently of iron levels. This means a high ferritin does not automatically indicate iron overload.
Common causes of elevated ferritin, grouped by mechanism:
Iron overload
Hereditary haemochromatosis is the most common genetic iron overload condition. The HFE gene mutation leads to excessive intestinal iron absorption and accumulation in organs including the liver, heart, and joints. Ferritin is markedly elevated (often >1000 ng/mL in established disease) alongside high transferrin saturation (>45–50%). Diagnosis requires genetic testing and clinical evaluation, not ferritin alone.
Iron overload can also result from repeated blood transfusions (transfusional iron overload) in conditions such as thalassaemia or myelodysplastic syndrome.
Inflammation and infection
Ferritin rises with acute infection, autoimmune disease (rheumatoid arthritis, lupus), inflammatory bowel disease, and other inflammatory states. In this context, elevated ferritin reflects the acute-phase response rather than iron stores. Serum iron and transferrin saturation are usually low in this setting, in contrast to iron overload where TSAT is high.
Liver disease
Ferritin is produced by liver cells. Liver inflammation — from alcohol, fatty liver disease (NAFLD/MASLD), viral hepatitis, or other causes — causes ferritin to leak into the bloodstream, raising the level. ALT, AST, and other liver tests are usually elevated in parallel.
Metabolic syndrome and obesity
Insulin resistance and visceral adiposity are associated with mildly to moderately elevated ferritin, likely through low-grade inflammation and liver involvement. This is common and does not necessarily indicate haemochromatosis or iron overload.
Haematological conditions
Some blood cancers (lymphoma, leukaemia, myeloproliferative disorders) and other haematological conditions can cause significantly elevated ferritin, sometimes extremely high levels. Hyperferritinaemia in this context may accompany systemic symptoms and abnormal full blood count findings.
Still's disease (adult-onset)
Very high ferritin (>10,000 ng/mL in some cases) combined with fever, rash, and joint pain can be a feature of adult-onset Still's disease or macrophage activation syndrome — rare but important diagnoses that require specialist evaluation.
How clinicians interpret ferritin — the key additional tests
Because ferritin alone is insufficient in many situations, clinicians typically interpret it alongside other markers. The most important companion tests are:
- Transferrin saturation (TSAT): High TSAT + high ferritin suggests iron overload. Low TSAT + low ferritin = iron deficiency. Low TSAT + elevated ferritin = anaemia of chronic disease / inflammation masking iron deficiency.
- Haemoglobin and MCV: Iron deficiency anaemia produces a low haemoglobin and small red cells (microcytic anaemia). Ferritin will be low.
- CRP or ESR: Markers of inflammation. If these are elevated alongside a raised ferritin, the ferritin elevation may be inflammatory rather than indicating iron overload.
- Liver function tests (ALT, AST, GGT): Help identify liver disease as the cause of elevated ferritin.
- HFE gene testing: If haemochromatosis is suspected (high ferritin + high TSAT with no other obvious cause), genetic testing for the C282Y and H63D HFE mutations is standard practice.
Frequently asked questions
What is a normal ferritin level?
Reference intervals vary by laboratory, sex, and age. Typical adult ranges are roughly 12–300 ng/mL for men and 12–150 ng/mL for women, but labs differ. Use the range on your own report. Some clinicians prefer ferritin above 30–50 ng/mL to confidently rule out iron deficiency, even when the result is technically within range.
Can ferritin be normal but iron still be low?
Yes. Ferritin is an acute-phase reactant — it rises with inflammation, infection, liver disease, and other conditions. Someone with iron deficiency and concurrent inflammation may have a ferritin within or even above the reference range, masking the deficiency. Clinicians often order transferrin saturation (TSAT) and serum iron alongside ferritin for a more complete picture.
Is a ferritin of 10 ng/mL dangerous?
A ferritin of 10 ng/mL is low and indicates depleted iron stores. Whether it requires treatment depends on your symptoms (fatigue, shortness of breath, restless legs), haemoglobin level, and clinical context. Your clinician will assess this in combination with other findings rather than acting on ferritin alone.
Should I take iron supplements if my ferritin is low?
Do not start iron supplements without medical advice. While iron supplements are the standard treatment for iron deficiency, taking them without investigation may delay identifying an underlying cause (such as GI blood loss) that requires its own treatment. Your clinician will also advise on the appropriate form and dose.
Why is my ferritin high when I feel fine?
Mildly elevated ferritin in the absence of symptoms is common and often reflects low-grade inflammation, metabolic syndrome, or alcohol intake rather than significant iron overload. Your clinician will interpret this alongside transferrin saturation, liver tests, and your history. Significant or progressive elevation warrants further investigation.
Trusted reference sources
- MedlinePlus: Ferritin blood test (U.S. National Library of Medicine)
- NHS: Iron deficiency anaemia
- Haematology Society of Australia & New Zealand: Iron deficiency
- Mayo Clinic: Ferritin test
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