Ferritin
Ferritin is a protein that stores iron inside cells, primarily in the liver, spleen, and bone marrow. Blood ferritin reflects total body iron stores — it is the most sensitive and specific test for iron deficiency. Unlike serum iron, ferritin does not fluctuate with meals or time of day. However, ferritin also rises during inflammation, infection, and liver disease.
Reference Ranges
Male
30 – 400
ng/mL
Female
15 – 150
ng/mL
Child
7 – 140
ng/mL
Ages 1–18, varies by age
Reference ranges may vary by laboratory. Always compare with the range printed on your lab report.
What Low Levels Mean
Low ferritin (below 30 ng/mL in adults) is diagnostic of depleted iron stores. Even before anemia develops, low ferritin causes fatigue, weakness, hair loss, restless legs, poor concentration, and increased susceptibility to infections. Women of reproductive age are most commonly affected due to menstrual blood loss.
What High Levels Mean
High ferritin can indicate iron overload (hemochromatosis), liver disease, chronic inflammation, infection, or certain cancers. Very high ferritin (>1000 ng/mL) needs urgent investigation. In acute infection or inflammation, ferritin is an acute-phase reactant and may rise dramatically without reflecting true iron excess.
Frequently Asked Questions
What ferritin level indicates iron deficiency?
Below 30 ng/mL confirms iron depletion. Below 15 ng/mL is definitive iron deficiency. However, if inflammation is present, ferritin can be 'falsely normal' — a ferritin of 50 in the setting of high CRP may still represent iron deficiency. Some experts use a threshold of 100 ng/mL when inflammation coexists.
Can ferritin be high without iron overload?
Yes. Ferritin is an acute-phase reactant — it rises in inflammation, infection, liver disease, and cancer. COVID-19, for example, can dramatically elevate ferritin. To distinguish true iron overload from reactive elevation, check transferrin saturation and C-reactive protein (CRP).
How long does it take to replenish ferritin?
With iron supplements, hemoglobin usually improves within 2–4 weeks, but ferritin takes 3–6 months to normalize. Doctors recommend continuing iron supplements for 3 months after hemoglobin normalizes to fully replenish stores. Premature stopping is the most common reason for relapse.
This information is for educational purposes only and should not replace professional medical advice. Always consult your doctor for interpretation of your test results.
Read Full Medical Disclaimer →