Iron deficiency anemia is caused by low iron levels in the body, which may be the result of a reduced ability of your digestive tract to absorb iron. Conditions that may lower your body's absorption of iron include:

• Total or partial removal of the stomach (gastrectomy).
• Surgery that helps people lose weight (bariatric surgery).
• Lack of stomach acid (achlorhydria).
• Total or partial removal of the small intestine.
• Chronic diarrhea.
• Small-bowel disease, such as celiac disease.