Iron deficiency: a plain-language primer

What it is

Iron is needed to make hemoglobin, the protein in red blood cells that carries oxygen around the body. Iron deficiency means the body’s iron stores are too low. It can cause symptoms even before anemia develops. Iron-deficiency anemia occurs when iron deficiency leaves the blood without enough healthy red blood cells or hemoglobin to carry oxygen effectively. (Sources: Recommendations for Diagnosis, Treatment, and Prevention of Iron Deficiency and Iron Deficiency Anemia; Cleveland Clinic; Mayo Clinic)

Common causes

Iron deficiency generally results from one or more of the following:

• Blood loss: Heavy menstrual bleeding and slow bleeding from the stomach or intestines are common examples. Gastrointestinal bleeding may be related to ulcers, bowel disease, or, less commonly, cancer. (Sources: American Academy of Family Physicians; American Medical Association)
• Not getting enough iron: A diet that does not provide enough iron can contribute. (Source: Cleveland Clinic)
• Poor absorption: Celiac disease, inflammatory bowel disease, gastrointestinal surgery, and some other digestive conditions can interfere with iron absorption. Long-term use of proton-pump inhibitors may also reduce absorption. (Sources: American Society of Hematology; Recommendations for Diagnosis, Treatment, and Prevention of Iron Deficiency and Iron Deficiency Anemia)
• Increased need: Pregnancy and periods of rapid growth can increase iron requirements. (Sources: Cleveland Clinic; American Academy of Family Physicians)
• Chronic illness or inflammation: Conditions such as chronic kidney disease, cirrhosis, and heart failure can disrupt how iron is stored and used and can make test results harder to interpret. (Source: American Society of Hematology)
• Rare inherited causes: Iron-refractory iron-deficiency anemia is uncommon and usually appears in childhood. (Source: *Recommendations for Diagnosis,