Ferritin is a protein that stores iron in your body, so a ferritin test is a window into your iron reserves. It is often used to look into anemia or fatigue. Here is how to read yours.
Ferritin is a protein that stores iron and releases it when your body needs it. Measuring ferritin gives an indirect look at how much iron you have in reserve, which is why it is often ordered when someone has anemia, unexplained tiredness, or a suspected iron problem. It is reported in ng/mL.
Reference ranges vary by laboratory and by sex, so read your value against the range on your own report. A low ferritin generally points toward low iron stores, which can occur before anemia fully develops. A high ferritin has several possible causes and is interpreted differently. Your clinician reads it in context.
Low ferritin often reflects iron deficiency, which can come from diet, blood loss, or increased needs. A high ferritin can be linked to inflammation, liver conditions, or iron overload, among other causes, because ferritin also rises with inflammation. This is why the same number can mean different things, and why follow-up depends on your full picture.
Upload your lab report and Mednex reads ferritin alongside hemoglobin in plain language, and tracks it so your next result compares against this one.
Decode my labsContent last reviewed 9 July 2026. Reference ranges vary by laboratory; always read your results against the range printed on your own report.
This page explains a common lab marker in general terms using public information from the U.S. National Library of Medicine and other NIH sources. It is educational and is not a diagnosis or medical advice. Reference ranges differ between laboratories and the meaning of a result depends on your age, sex, medications, and overall health. Always discuss your own results with the clinician who ordered them.