Ferritin
Also known as: Serum ferritin
Ferritin is the body's primary iron storage protein and the most sensitive blood test for detecting iron deficiency — it falls before haemoglobin or serum iron does. But it is also an acute-phase reactant, which means inflammation can mask deficiency.
Venous blood (serum separator tube)
24 hours
Not required
Vitamins & Minerals
Reference Ranges
| Measurement | Reference Range | Unit |
|---|---|---|
| Men | 30 – 400 | ng/mL |
| Women (premenopausal) | 13 – 150 | ng/mL |
| Women (postmenopausal) | 13 – 200 | ng/mL |
Reference ranges are typical adult values. Your laboratory may use slightly different intervals — always use your lab's reported reference.
What This Test Measures
Each ferritin molecule stores up to 4,500 iron atoms in its hollow core, releasing them when tissues need iron for oxygen transport, DNA synthesis, and enzyme function. The serum ferritin level correlates closely with total body iron stores — 1 ng/mL represents approximately 8 mg of stored iron. Unlike serum iron, ferritin is not affected by recent iron intake.
When Is This Test Ordered?
- Investigating fatigue, hair loss, restless leg syndrome, or poor concentration
- Confirming iron-deficiency anaemia before treating
- Ruling out iron overload in haemochromatosis screening
- Monitoring inflammatory or oncological conditions (as an acute-phase protein)
- Before blood donation — some centres screen ferritin rather than haemoglobin alone
When Results Are High
High ferritin with high transferrin saturation suggests iron overload. High ferritin alone (without high saturation) is usually an inflammatory or hepatic signal — liver disease, metabolic syndrome, alcohol use, infection, and malignancy all raise ferritin without true iron excess. This distinction requires the full iron panel.
When Results Are Low
Low ferritin (below 30 ng/mL) is iron deficiency — even if haemoglobin is still normal. Symptoms at this stage include fatigue, brain fog, hair shedding, and pica. Ferritin below 15 ng/mL is virtually diagnostic for iron deficiency in the absence of confounding factors.
The ferritin paradox: normal number, real deficiency
A ferritin of 60 ng/mL looks reassuringly normal — but if the patient has an active infection with CRP of 40 mg/L, the inflammation has boosted ferritin by 30–50 ng/mL. The true ferritin — corrected for inflammation — may be 10–30 ng/mL, squarely in the deficiency range.
Functional iron deficiency is another scenario: in chronic kidney disease patients receiving erythropoietin (EPO) therapy, ferritin may be 100–200 ng/mL yet iron delivery to the marrow is insufficient because EPO drives demand faster than stores can supply. These patients still benefit from IV iron.
Factors That Can Affect Your Result
- Inflammation from any cause raises ferritin — CRP should always be checked alongside ferritin to interpret the result
- Liver damage releases intracellular ferritin, raising serum levels acutely
- Alcohol raises ferritin both as an acute-phase response and via liver damage
- Metabolic syndrome is associated with chronically elevated ferritin (50–200 ng/mL) without iron overload
Tracking This Test Over Time
If your ferritin is below 30 ng/mL but CRP is elevated, the true ferritin may be even lower than measured. Request a repeat ferritin after the inflammation resolves, or use soluble transferrin receptor (sTfR), which is not affected by acute-phase responses.
Track your Ferritin in LoomsRelated Tests
Iron Studies
Iron studies go beyond a simple iron level to measure the body's full iron storage and transport system — serum iron, ferritin, transferrin saturation, and TIBC — giving a complete picture of iron status.
CBC
A CBC measures all three types of blood cells — red cells, white cells, and platelets — along with haemoglobin and haematocrit. It is one of the most ordered tests in medicine because it screens for dozens of conditions in a single draw.
CRP
CRP is a protein released by the liver in response to inflammation. Depending on which assay is ordered, it serves as either a sensitive general inflammation marker (standard CRP) or a cardiovascular risk predictor (high-sensitivity CRP, hs-CRP).
Medical disclaimer
This page is for educational purposes only and does not constitute medical advice. Reference ranges vary between laboratories, and results must be interpreted in the context of your symptoms, history, and other tests. Always discuss your results with your healthcare provider. Content reviewed by the Looms medical team, 2026-06-01.