Ferritin Test: What It Shows, Normal Range for Women and Men

What the ferritin test shows

Ferritin is the protein that stores iron inside your cells, and the amount circulating in blood — serum ferritin — is proportional to how much iron your body has banked. That makes it the single most useful marker of iron status. MedlinePlus calls it the test that estimates how much iron is stored in your body.

It differs from the markers it is ordered with. Hemoglobin measures iron already carrying oxygen inside red blood cells; serum iron measures iron travelling in the blood at that moment, which swings with meals and time of day. Ferritin reflects the reserve, which is spent first — so it drops before hemoglobin falls and before anemia appears, catching iron deficiency at a treatable stage, as StatPearls notes.

Its main limitation is that ferritin is also an acute-phase protein: inflammation, infection and liver injury push it up regardless of iron stores, so one value is read in context.

Ferritin normal range

Ferritin is reported in ng/mL, numerically identical to the SI unit µg/L (1 ng/mL = 1 µg/L), so US and European reports mean the same thing. Typical adult orientation ranges:

Two thresholds matter more than the “normal” band. The WHO defines depleted iron stores as ferritin below 15 µg/L in adults (12 µg/L in children under 5). In practice many clinicians, and NICE in the UK, treat anything below 30 ng/mL as iron deficiency — a far more sensitive cutoff that flags people before anemia sets in. Reference ranges depend on the lab, sex and age — always read your result against your own report.

Why ferritin is low

A low ferritin is the most specific blood test for iron deficiency — essentially nothing else lowers it. The question is not whether iron is low but why:

• Blood loss (commonest in adults). In women of reproductive age, heavy periods lead. In men and postmenopausal women, deficiency without an obvious cause points to the gut — a slow bleed from an ulcer, polyp or colorectal cancer can show up first as low ferritin.
• Increased demand: pregnancy, childhood and adolescent growth, endurance training.
• Low intake: diets very low in bioavailable iron, including unplanned vegetarian or vegan patterns.
• Malabsorption: celiac disease, Helicobacter pylori, autoimmune gastritis, bariatric surgery, long-term acid-suppressing medication.

Symptoms often appear while ferritin is low but hemoglobin is still normal — iron deficiency without anemia. Fatigue, breathlessness on exertion, brittle nails, restless legs and diffuse hair loss are typical, and overlap with an underactive thyroid, so ferritin and TSH are often checked together.

When is it urgent? Iron deficiency with no obvious source, especially in a man or postmenopausal woman, should prompt evaluation of the gut without long delay. Severe anemia symptoms — chest pain, marked breathlessness or fainting — need same-day care.

Why ferritin is high

High ferritin is common and, most of the time, is not iron overload. Roughly by frequency:

• Inflammation and infection. As an acute-phase reactant, ferritin rises with any recent illness, autoimmune flare or chronic inflammation — which is why it is read alongside CRP.
• Metabolic causes: fatty liver, metabolic syndrome, type 2 diabetes, obesity and regular alcohol use are among the commonest reasons for a mildly-to-moderately raised ferritin.
• Liver disease of any cause, as damaged cells release stored ferritin.
• True iron overload: hereditary hemochromatosis (usually the HFE C282Y variant) or repeated transfusions.

The way to tell overload from the rest is transferrin saturation. High ferritin with saturation above about 45% warrants an iron-overload work-up, including HFE genetic testing, per StatPearls; when saturation is normal or low, the cause is usually inflammation, liver or metabolic.

When is it urgent? A very high value — in the thousands, especially above 10,000 ng/mL — can signal serious disease (adult-onset Still’s disease, hemophagocytic lymphohistiocytosis, severe liver injury, malignancy) and needs prompt assessment.

What to test alongside

Ferritin is rarely interpreted on its own. Order it with the core iron panel and a few cross-checks:

• Serum iron — iron circulating now.
• TIBC — iron-binding capacity; rises in deficiency.
• Transferrin — the iron transport protein.
• Transferrin saturation — separates overload from other causes of high ferritin.
• Soluble transferrin receptor — reliable when inflammation clouds ferritin.
• Hepcidin — the master iron-regulating hormone (specialist use).
• Hemoglobin — shows whether the shortage has reached anemia.
• CRP — flags inflammation that can falsely raise ferritin.
• TSH and vitamin D — co-causes of the same fatigue and hair loss.
• ALT — a liver check when ferritin is high.

What to do about an abnormal result

1. Don’t self-treat. Iron taken without a diagnosis can mask a bleeding source, and in undiagnosed hemochromatosis it adds to overload.
2. Repeat in context. Ferritin swings with illness, so recheck an abnormal value when you are well, paired with CRP.
3. For low ferritin: your primary-care doctor looks for the source of loss (periods, gut symptoms, diet), replaces iron by mouth, and rechecks after about 8–12 weeks, as stores refill slowly. Unexplained deficiency may prompt a gastroenterology or gynecology referral.
4. For high ferritin: the first step is transferrin saturation plus CRP, pointing either to an inflammation, liver or metabolic work-up or to a hematology referral for suspected overload.
5. See your GP or primary-care physician first; they coordinate the next test rather than jumping to treatment.

Mini-FAQ

How is ferritin different from hemoglobin?

Hemoglobin is the iron already working inside red blood cells; ferritin is the iron held in storage. Because stores empty first, ferritin falls before hemoglobin, flagging a shortfall earlier.

What ferritin level counts as low?

The WHO calls iron stores depleted below 15 ng/mL in adults, but many clinicians and NICE now treat below 30 ng/mL as iron deficiency because it catches far more cases. Thresholds rise with inflammation.

Can ferritin be normal or high while you are still iron deficient?

Yes. Ferritin rises with inflammation, infection, liver disease and obesity, so it can read normal or high while iron stores are low — which is why it is paired with CRP and transferrin saturation.

What does a high ferritin usually mean?

Usually inflammation, fatty liver or metabolic syndrome rather than true iron overload. High ferritin with a transferrin saturation above about 45% prompts a work-up for hereditary hemochromatosis.

How do I raise a low ferritin?

Treat the cause, such as heavy periods or another source of blood loss, and replace iron as your doctor directs, usually by mouth. Stores refill slowly, so ferritin is rechecked after about 8–12 weeks; do not start high-dose iron on your own.