Ferritin
The protein that stores iron, used as a proxy for iron reserves.
What it measures
The concentration of ferritin, the protein that stores iron inside cells. It is used as an indirect measure of total body iron stores.
Why a doctor orders it
The most useful single test for assessing iron stores, ordered when anemia, fatigue, or iron overload is being considered.
What is generally associated with a higher result
Broadly associated with iron overload conditions, but also - importantly - with inflammation, infection, liver disease, and alcohol, because ferritin rises as part of the inflammatory response regardless of iron.
What is generally associated with a lower result
A low ferritin is fairly specific for depleted iron stores, and can be present before anemia develops.
Everyday things that move this number
Not every shift in a value reflects disease. These are ordinary factors known to affect this particular measurement:
- Any active inflammation or infection, which raises it independently of iron
- Liver conditions
- Recent iron supplementation
Questions to take to your appointment
- Could inflammation be raising this and masking low iron?
- Should a CRP be checked alongside it?
Build a printable questionnaire with your own results →
Where to read more
MedlinePlus, from the US National Library of Medicine, publishes patient-facing pages on individual lab tests and is a reliable next stop: medlineplus.gov/lab-tests .
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