What Ferritin measures
Ferritin is the protein that stores iron inside your cells. A small amount circulates in the blood in proportion to those stores, so a ferritin test is the most common way to check whether iron reserves are running low or building up.
It is often tested with other iron markers such as serum iron, transferrin saturation and haemoglobin.
Why it matters for longevity
Iron is needed to make red blood cells and for energy metabolism. Low stores are common, especially in people who menstruate, donate blood regularly, or eat little or no meat, and can contribute to tiredness.
Iron can also build up over the years, which is why a high result is followed up by a doctor too. Because ferritin rises with inflammation, it is best read alongside hs-CRP.
How it's tested
- Sample
- Finger-prick or venous
- Fasting
- Not needed for ferritin alone; some iron panels ask for a morning or fasting sample
- Units
- µg/L (the same as ng/mL)
Before you test
- If you take iron supplements, ask the provider whether to pause them before testing.
- Avoid testing while you're unwell, as illness can raise ferritin.
What can affect your result
- Inflammation or infection, which raise ferritin temporarily
- Recent iron supplements or blood donation
- Heavy periods or pregnancy
- Alcohol and liver conditions
Talking to your doctor about your result
Your report will show your result next to the lab's reference range. Ranges differ between labs and units, and a result inside or outside the range isn't a diagnosis on its own. Share the full report with your doctor – especially if a result is flagged, you have symptoms, or there's a family history that concerns you. Don't start, stop or change any medicine or supplement based on a home test without medical advice.
What a Ferritin test costs
We haven't recorded a single-test price for Ferritin yet – it's most often bought as part of a panel. See what panels cost by country in our European blood test price guide.
Ferritin: common questions
Why test ferritin together with hs-CRP?
Ferritin rises with inflammation, so a normal-looking ferritin can hide low iron stores if hs-CRP is raised. Looking at both together gives a clearer picture.
Should I take iron if my ferritin is low?
Don't start iron supplements based on a single result without speaking to a doctor or pharmacist. Too much iron can be harmful, and the reason for low stores matters.
Can I test ferritin at home?
Yes. Ferritin is included in many finger-prick panels, often alongside a basic full blood count.
Related markers
Sources
[PLACEHOLDER: 2–4 primary references (guidelines, consensus statements) confirmed by the medical reviewer]