Ferritin is the protein in which the body stores iron. Its blood level reflects iron stores in the depot, not how much iron is circulating right now.
That is exactly why ferritin is the earliest marker of iron deficiency: it falls long before hemoglobin drops. A person can have a perfectly normal hemoglobin and already suffer from latent iron deficiency.
Reference ranges
The reference range varies widely between labs; approximate adult values:
| Men | 30 – 400 ng/mL |
| Women | 15 – 150 ng/mL |
| Iron deficiency | below 30 ng/mL |
| Optimum (in the view of many clinicians) | 70 – 100 ng/mL |
| Elevated | above the lab's upper limit |
What an elevated level means
Elevated ferritin is harder to interpret because the causes are diverse.
Most often it is not iron excess but inflammation: ferritin is an acute-phase protein and rises with infections, autoimmune disease, obesity, liver disease and cancer. So an isolated high ferritin with normal transferrin saturation usually means inflammation, not iron overload.
True iron overload (hemochromatosis) is accompanied by both high ferritin and high transferrin saturation — this requires evaluation by a doctor.
What a low level means
Low ferritin is the earliest and most reliable sign of iron deficiency. A value below 30 ng/mL indicates depleted stores even if hemoglobin is still normal (latent deficiency).
Symptoms: fatigue, weakness, hair loss, brittle nails, pallor, shortness of breath on exertion, restless legs syndrome, reduced concentration.
Causes: blood loss (heavy periods, hidden GI bleeding), insufficient dietary intake, malabsorption (celiac disease, gastritis), pregnancy, blood donation, vegetarianism.
How the test is done
Venous blood, preferably in the morning. Strict fasting is not required, but it is better to test fasting and under consistent conditions.
Important: do not test ferritin during or right after an acute illness — inflammation will raise it and make the result useless. Wait 2–4 weeks after recovery. Stop iron supplements at least a week beforehand.
What affects the value
- Inflammation and infections — raise ferritin regardless of iron stores.
- Blood loss — the main cause of a drop (including heavy periods).
- Iron supplements — distort the result unless stopped in advance.
- Vitamin C — improves dietary iron absorption; tea and coffee, conversely, worsen it.
- Liver disease and alcohol — raise ferritin.
- Vegetarianism — plant (non-heme) iron is absorbed considerably worse.
Calculate using this marker
Calculators where Ferritin is used directly:
Frequently asked questions
Hemoglobin is normal but ferritin is low — does that happen?
Yes, and it is very common. It is called latent (hidden) iron deficiency: the stores are already depleted, but the body still keeps hemoglobin normal. The symptoms — fatigue and hair loss — are already there.
My ferritin is high — do I have iron excess?
Probably not. Much more often high ferritin means inflammation, obesity or liver problems, because it is an acute-phase protein. True iron overload is indicated by the combination of high ferritin and high transferrin saturation.
What ferritin should be considered optimal?
The formal lower limit of normal (15–30 ng/mL) is very low: at such values deficiency symptoms are usually already present. Many clinicians consider a target of 70–100 ng/mL, especially with complaints of fatigue and hair loss.