Short answer for adults: labs print a wide "normal" range, and many set the low end at 12–15 µg/L. But below about 50 µg/L your iron stores are often low — and below about 30 µg/L they usually are — even if it isn't flagged.
What ferritin is
Ferritin is a protein that stores iron inside your cells. A small amount circulates in your blood, and that's what the test measures. Think of it as a fuel gauge for stored iron — useful, but not perfect.
Reading the number (adults)
- Below about 30 µg/L — iron stores are usually low.
- 30–50 µg/L — can still be low, especially if you have symptoms.
- Higher levels — your doctor reads them alongside your other results.
- Very high levels — can have other causes; your doctor will look into them.
Why the same number can mean different things
- Children, pregnancy and after childbirth use different cut-offs. Ask your doctor.
- Inflammation or infection can raise ferritin, so a normal-looking number doesn't always rule out low iron. Your doctor may check iron saturation (TSAT) and hemoglobin too.
- Right after an iron infusion, ferritin jumps for a while. Doctors usually recheck several weeks later to see your true level.
What to do with your number
Bring it to your doctor with your other results and how you've been feeling. They'll decide whether you need treatment, and which kind.