Ferritin
Ferritin is the protein that stores iron. The test shows the body’s iron stores; with inflammation it can read higher than the actual stores.
At a glance
- Sample
- Blood
- Units
- ng/mL (US), µg/L (Europe): the same number
- Often looked at with
- Iron, Transferrin, TIBC, Transferrin saturation
- Preparation
- Labs often ask you to come in the morning, fasting, especially when iron is tested at the same time.
Units: ng/mL and µg/L
US labs usually print ferritin in ng/mL, many European labs in µg/L. Both are a mass per volume, and the prefixes cancel out: the number stays the same.
Why lab ranges differ
Each lab sets its reference range for its own method and analyser, and many ranges differ by age and sex. Two labs can print different ranges for the same blood, so a result is read against the range on its own report, not against a number from another lab or a website.
Soma charts every ferritin result against the range printed by the lab that measured it.
What can affect the result
- A recent cold or inflammation: ferritin rises with inflammation, which can hide low iron stores.
- Iron supplements.
- Alcohol the day before.
If something like this applies, mention it to the doctor who reads your results.
Questions
Is ferritin in ng/mL the same as in µg/L?
Yes. One ng/mL is exactly one µg/L, so 40 ng/mL and 40 µg/L are the same result.
Why does my lab’s ferritin range differ from another lab’s?
Each lab sets its range for its own method and equipment, and many ranges differ by age and sex. That’s why a result is best read against the range printed on the same report.
How do I prepare for a ferritin test?
Labs often ask you to come in the morning, fasting, especially when iron is tested at the same time. Follow your lab’s instructions.
Related tests
Got a lab report with Ferritin?
Share it to Soma: it reads every row on your phone, with no account and no upload, and puts your ferritin on one chart with your earlier results, each against the range your lab printed.
Sources
- Ferritin Blood Test — MedlinePlus, U.S. National Library of Medicine.
- Units: 1 ng/mL = 1 µg/L by the metric prefixes, as the Soma app converts.
Mention of a source doesn’t mean it endorses Soma. This page explains the test; it doesn’t diagnose and is not medical advice. Talk to your doctor about what your results mean.