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Ferritin Levels
Ferritin levels help show how much iron your body has stored. This guide explains what ferritin is, how it helps identify iron deficiency, and how WHO thresholds change by age and health.
Updated September 2026
What is ferritin?
Ferritin is a protein that stores iron. A blood test measures serum or plasma ferritin to estimate stored iron. A low result can support a diagnosis of iron deficiency. Ferritin is also used when checking for iron overload.
WHO ferritin level thresholds
WHO uses different ferritin cut-offs for age, pregnancy, infection and inflammation. The table shows iron deficiency and iron overload risk thresholds in µg/L.
Swipe the table sideways to see every column.
| Age or group | Iron deficiency | Risk of iron overload | ||
|---|---|---|---|---|
| Apparently healthy | Infection or inflammation | Apparently healthy | Non-healthy | |
| Infants, 0 to 23 months | <12 | <30 | Not given | Not given |
| Preschool children, 24 to 59 months | <12 | <30 | Not given | Not given |
| School-age children, 5 to 12 years | <15 | <70 | >150 female, >200 male | Not given |
| Adolescents, 13 to 19 years | <15 | <70 | >150 female, >200 male | Not given |
| Adults, 20 to 59 years | <15 | <70 | >150 female, >200 male | >500 |
| Older adults, 60 years and older | <15 | <70 | >150 female, >200 male | >500 |
| Pregnant patients | <15 in the first trimester | Not given | Not given | Not given |
For ferritin, µg/L and ng/mL have the same numeric value. “Not given” means WHO did not provide a cut-off for that group.
WHO says inflammation markers should be checked with ferritin. Ferritin above 500 µg/L in a non-healthy adult may point to iron overload or another disease and needs more review.
The pregnancy cut-off in this table applies to the first trimester.
Source: World Health Organization, Guideline on Use of Ferritin Concentrations to Assess Iron Status in Individuals and Populations (2020).
How ferritin helps diagnose iron deficiency
Ferritin reflects stored iron. Serum iron shows iron circulating when the sample is taken. Hemoglobin measures the oxygen-carrying protein in red blood cells.
Iron deficiency can be present while hemoglobin is still normal. The ASH report found that low laboratory reference limits can miss iron deficiency without anemia.
Infection and inflammation can raise ferritin. A clinician may use ferritin with hemoglobin, transferrin saturation and inflammation markers. Our iron blood work test guide shows how these markers are read together.
What happens after a low ferritin result?
Treatment depends on why iron is low. A clinician may review blood loss, iron intake, absorption, inflammation and other blood tests.
Oral iron may be discussed first. IV iron may be discussed when oral iron is not tolerated, not absorbed or has not worked. Our guide explains how IV iron may affect hemoglobin. You can also read about iron infusion in Edmonton.
Medical sources
- 1. World Health Organization. New thresholds for the use of ferritin concentrations to assess iron status in individuals and populations.
- 2. The Metabolic Journal. Iron Blood Test: Ferritin, TIBC, Iron Saturation and How to Interpret Your Results.
- 3. Morgan C, Ma A, Rivenbark J, et al. Ferritin reference ranges and improving diagnosis of iron deficiency without anemia. Blood. 2025;146(Supplement 1):2609.
Frequently Asked Questions
What is a bad ferritin level?
WHO lists iron deficiency below 15 µg/L for an apparently healthy adult and below 70 µg/L when infection or inflammation is present. Age and pregnancy change the cut-off.
How do you fix your ferritin level?
Treatment depends on the cause. Low ferritin may be treated with oral iron or, in some cases, IV iron. A clinician should review the result before treatment changes.
Is it better to have low or high ferritin?
Neither. Low ferritin can mean iron stores are depleted. High ferritin can occur with iron overload, infection or inflammation.
Is ferritin a tumor marker?
The WHO guideline uses ferritin to assess iron status and as part of the work-up for iron overload. It does not describe ferritin as a stand-alone tumor marker.
What level of ferritin is life threatening?
WHO does not name one ferritin level as life threatening. Ferritin above 500 µg/L in a non-healthy adult may point to iron overload or another disease and needs more review.
Is it worse to have low iron or low ferritin?
They measure different things. Serum iron shows circulating iron when the sample is taken. Ferritin shows stored iron, so low ferritin gives stronger evidence of depleted iron stores.
This page is general health information. A clinician must review your result with your health history and other blood tests.