- Measures
- Stored iron
- Low suggests
- Iron deficiency
- High can reflect
- Iron overload or inflammation
- Women's iron needs after 50
- 8 mg per day
Why ferritin is useful
Iron is needed to make hemoglobin, which carries oxygen in red blood cells. Your body keeps a reserve tucked inside ferritin. When reserves fall, ferritin drops, often before you become anemic. That makes it an early warning sign of iron deficiency.
When ferritin is low
Low ferritin almost always means low iron stores. Common causes include:
- Heavy menstrual bleeding, which is a frequent cause in perimenopause.
- Slow bleeding from the digestive tract, from ulcers, frequent aspirin or NSAID use, inflammatory bowel disease or colon cancer.
- Poor absorption, as in celiac disease, after weight-loss surgery or with some stomach conditions.
- Low dietary intake, frequent blood donation or endurance training.
When ferritin is high
High ferritin can mean iron overload, such as hereditary hemochromatosis, but it often doesn't. Ferritin also rises with inflammation, infection, liver disease, heavy alcohol use, obesity, some cancers and an overactive thyroid. A high result is usually followed by further iron studies and other tests to sort out the cause.
Why ferritin matters in midlife
Iron deficiency can cause fatigue, shortness of breath with exertion, dizziness, cold hands and feet and restless legs, symptoms that are easy to blame on age or stress. Women with heavy perimenopausal periods are at particular risk.
After menopause, the recommended daily iron intake for women drops from 18 mg to 8 mg, and iron can slowly accumulate, especially in people with hemochromatosis. That's one reason not to take iron supplements 'just in case.' Too much iron can cause stomach problems, and very high doses are dangerous.
Interpreting the number
Reference ranges vary by lab, sex and age. A ferritin result that falls inside the lab's normal range can still be paired with symptoms of iron deficiency, and a normal-looking ferritin can hide deficiency when inflammation is present. Unexplained iron deficiency in a man or a postmenopausal woman generally warrants an evaluation for gastrointestinal blood loss.
If your ferritin is low, your clinician will usually look for the cause as well as replacing iron, since treating the number without finding the reason can miss something important. Iron can be given as tablets or, when tablets don't work or aren't tolerated, by infusion. Rechecking ferritin after a few months shows whether stores are recovering. Iron supplements can also interfere with absorption of some medicines, including levothyroxine, so timing matters.
Ferritin: common questions
Is ferritin the same as iron?
No. Ferritin reflects stored iron. Serum iron measures iron circulating in the blood at that moment, which changes more from day to day.
Can I have low ferritin without anemia?
Yes. Iron stores usually fall before hemoglobin does, so low ferritin can appear before anemia develops.
Does inflammation affect ferritin?
Yes. Infection, inflammation and liver disease can raise ferritin and hide an underlying iron deficiency.
Should I take iron if I feel tired?
Only if testing shows you need it. Unnecessary iron can build up over time and cause harm, especially with hemochromatosis.
Why would a man have low ferritin?
Men rarely become iron deficient from diet alone, so low ferritin in a man usually prompts a search for blood loss, often in the digestive tract.
Do I need to fast for a ferritin test?
Usually not for ferritin alone, though fasting may be required if other tests are drawn at the same time.
Sources
We cite government agencies, professional societies and peer-reviewed research. See our editorial policy.
- Ferritin Blood TestMedlinePlus (U.S. National Library of Medicine)
- Iron-Deficiency AnemiaNational Heart, Lung, and Blood Institute
- Iron: Fact Sheet for ConsumersNIH Office of Dietary Supplements