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Ferritin
A protein that stores iron. The ferritin level shows how much iron the body keeps in reserve — the earliest marker of iron deficiency, long before anemia develops.
Other names: Serum ferritin, ferritin serumSection: Iron status
Updated: August 29, 2026·MedProtect editorial team Reference information — not a diagnosis or a prescription
In shortFerritin reflects the body's iron stores. Common reference ranges are 30–400 ng/mL (30–400 µg/L) for adult men and 13–150 ng/mL (13–150 µg/L) for adult women. Values near the lower end can mean iron reserves are already depleted, even while hemoglobin is still normal. Laboratories set their own intervals, so the range printed on the report applies.
Reference ranges
Group
Reference range
Adult men
30–400 ng/mL (30–400 µg/L)
Adult women
13–150 ng/mL (13–150 µg/L)
These are the common reference values quoted in the MedlinePlus Medical Encyclopedia. Each laboratory sets its own interval, and some use different methods or samples — the range printed on the report is the one that applies.
Reference range vs optimal — not the same thing
“Within range” ≠ optimal. Iron deficiency without anemia is common at ferritin 30–50 ng/mL (especially in women); a common repletion target is above 50–100 ng/mL. Elevated ferritin is also a signal — inflammation or iron overload.
Check your value
Enter the number from your lab report — see how it compares with the typical range. Mind the units shown in the chosen row.
A rough comparison with a typical range, not a diagnosis. Reference ranges vary between laboratories — check the range on your own report and let a clinician interpret the result.
What this marker is
Ferritin is a protein inside cells that binds iron and keeps it in storage until the body needs it. Iron is required to build healthy red blood cells, which carry oxygen from the lungs to the rest of the body, and it also matters for muscles, bone marrow, and organ function, including brain development in children.
A ferritin blood test indirectly shows how much iron is stored. Unlike serum iron, which reflects only the iron circulating at the moment of the blood draw, ferritin answers a different question: whether the body's reserves are full, adequate, or running low.
Iron stores shrink gradually. Ferritin falls first, while hemoglobin and red blood cell counts can still sit inside their normal ranges. That is why the test often catches iron deficiency at an early, pre-anemia stage — and why a value at the lower edge of the range deserves attention even when nothing looks abnormal elsewhere.
Providers order ferritin as part of a group of iron tests. Typical reasons include checking for iron deficiency anemia or iron overload (hemochromatosis), looking into restless legs syndrome, and monitoring long-lasting conditions that can affect iron levels, such as kidney disease, cancer, or autoimmune disorders.
When it is high
Iron overload (hemochromatosis)The body stores more iron than it needs. Without treatment the excess settles in the liver, heart, and other organs.
Liver diseaseMuch of the body's ferritin sits in the liver, so inflammation or alcohol-related liver damage releases it into the blood.
Autoimmune conditionsRheumatoid arthritis and similar disorders raise ferritin as part of the inflammatory response, regardless of iron status.
Frequent red blood cell transfusionsEach transfusion adds iron that the body cannot actively remove, so stores — and ferritin — build up.
Overactive thyroid glandAn overactive thyroid is listed among the conditions that can come with elevated ferritin.
When it is low
Diet too low in ironThe most straightforward cause: not enough iron comes in to replenish what the body uses every day.
Heavy menstrual bleedingRegular monthly losses are the most common reason for low iron stores in women of reproductive age.
Hidden gastrointestinal bleedingSlow blood loss in the esophagus, stomach, or intestines can drain iron stores for months without visible signs.
Poor absorption of ironInflammatory bowel disease or a gastrointestinal operation can leave the gut unable to absorb enough iron from food.
Blood loss from an injuryA single significant bleed reduces both circulating iron and the reserves that ferritin reflects.
What can skew the result
These factors can shift the value without any disease — worth considering before a retest:
Active inflammation or infectionRecent blood transfusionTime of dayFasting state
How to prepare
A fasting sample is often requested: nothing to eat for up to 12 hours before the draw, and the test is usually scheduled for the morning. Water is fine. When ferritin is ordered together with other blood tests, the provider's instructions for the whole order apply.
When a retest makes sense
A single borderline value is rarely the whole story. During treatment for iron deficiency the test is used to check whether stores are actually recovering, which is slower than the hemoglobin response. Because inflammation can push ferritin up, a result measured during an active infection is sometimes re-checked once the illness has passed.
Who usually reviews this result
A result outside the reference range is usually reviewed by: your GP or primary care doctor; a hematologist if a blood disorder is suspected. Bring your lab report and any previous results to the appointment.
Names used on lab reports
Your report may use any of these names: FerritinSerum ferritinFerritin serumSerum ferritin level
Units and conversion
Measured in: ng/mL
ng/mL=µg/L
1 ng/mL = 1 µg/L — the number stays the same, only the unit label changes. Ferritin is the rare case where the two systems match exactly. Results are rounded to 2 decimal places.
Several markers on your report?
See how MedProtect explains results in the app: the whole report, a check of the recognized values, and a clear breakdown.
Not exactly. Ferritin drops first, when iron stores run low; anemia develops later, when there is no longer enough iron to produce hemoglobin. A person can have low ferritin with perfectly normal hemoglobin — this stage is sometimes called iron deficiency without anemia, and it can still cause fatigue and restless legs.
Can ferritin be high without iron overload?
Yes. Ferritin rises during inflammation and infection as part of the body's general response, and liver disease releases stored ferritin into the blood. A high value is therefore read together with the clinical picture — and often with other iron tests — before iron overload is considered.
Does the ferritin test require fasting?
Often it does: the MedlinePlus encyclopedia notes that the provider may ask for up to 12 hours of fasting and a morning draw. When the test is part of a larger order, the instructions for that order take priority.
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