The Marker You're Missing: Ferritin 

The Marker You're Missing: Ferritin

Why ferritin isn't as simple as an iron test

Ferritin is unusual among biomarkers because the same elevated number can mean two almost opposite things: too much stored iron, or inflammation with completely normal iron. It's the protein that stores iron in your body, and because it's more stable day-to-day than a standard iron test, it gives a better read on your long-term reserves. But your body also raises ferritin on purpose during illness or inflammation, pulling iron away from bacteria and viruses that need it to multiply. That means a high result doesn't automatically mean iron overload, and a normal result doesn't always rule out a problem either. Here's how to actually read your number.

More than an iron test →

What it is

Ferritin is the protein that stores iron in your liver, spleen, and bone marrow, and it reflects your long-term iron reserves better than a same-day iron blood test does.

Why it matters

It does double duty as both an iron marker and an inflammation marker, since your body deliberately raises ferritin during infection or inflammation regardless of how much iron you actually have. Reading it alongside a marker like CRP is usually what tells you which one you're looking at.