Ferritin
Also called Serum ferritin
Ferritin is a protein that binds and stores iron inside the body, and a ferritin blood test is the standard way to estimate how much iron is held in reserve. The body needs iron to make healthy red blood cells, which carry oxygen, and for muscles and organs to work normally.
Ferritin is usually ordered as part of a group of iron tests rather than alone, because it reads in two directions. Low ferritin points to depleted iron stores, which can lead to iron-deficiency anemia. High ferritin can mean iron overload, as in hemochromatosis, but it also rises with inflammation, infection, liver disease, obesity, alcohol use and an overactive thyroid, so a high result does not by itself mean too much iron. Interpretation lives on two dedicated pages: Low Ferritin: Why It Shows Up Before Anemia Does and What High Ferritin Means, and What It Does Not.
Why it matters after 45
The symptoms of low iron, including fatigue, weakness, shortness of breath and restless legs, overlap with complaints common in midlife, so ferritin often appears on a tiredness work-up. In adults, depleted iron calls for a reason: heavy menstrual periods, bleeding in the digestive tract from ulcers, inflammatory bowel disease or colon cancer, and regular use of aspirin or anti-inflammatory painkillers are all recognized causes. Too much iron causes its own midlife-sounding symptoms, such as joint pain, fatigue and loss of interest in sex.
Where it comes up
Related terms
References
- MedlinePlus. Ferritin Blood Test. U.S. National Library of Medicine. https://medlineplus.gov/lab-tests/ferritin-blood-test/
- MedlinePlus. Iron Tests. U.S. National Library of Medicine. https://medlineplus.gov/lab-tests/iron-tests/
- National Heart, Lung, and Blood Institute. Iron-Deficiency Anemia. https://www.nhlbi.nih.gov/health/anemia/iron-deficiency-anemia
Definitions here are educational and are not medical advice. They explain what a term means; the pages linked above cover what it means for you, and a clinician reviews your own results. Editorial & medical review policy · All glossary terms