Common Causes of Iron-Deficiency Anemia

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Iron is an essential part of your blood. In red blood cells, it’s required for a protein called hemoglobin to carry oxygen from your lungs to the rest of your body. Iron-deficiency anemia is when you don’t have enough iron in your system to make new blood cells able to carry oxygen. You end up with fewer red blood cells and your body gets less oxygen that it needs to function normally. This leads to the classic symptoms of iron-deficiency anemia, including fatigue, shortness of breath, and lightheadedness.

There are four common causes of low iron:

  • Needing more iron than your body is making (increased demand)
  • Loss of red blood cells from bleeding
  • Not being able to absorb enough iron from your diet
  • Not having enough iron in your diet

Increased Demand

You may need more iron if you are pregnant. Your body needs to make more red blood cells to supply your womb and your developing baby. More red cells can deplete your supply of iron. Doctors routinely check iron levels in pregnant women. A complete blood count test will check your level of hemoglobin. Other blood tests can check iron levels.

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Children who go through rapid growth spurts may also have iron deficiency. This commonly occurs around the age of nine months. Doctors will do a blood test to check hemoglobin levels by age one.

Increased Loss

If you are a woman who is having menstrual periods, you are at higher risk for iron loss through bleeding, especially if you have heavy periods. If you are menstruating, having heavy periods or have symptoms of anemia, your doctor may do blood tests to check for iron deficiency.&Other causes of increased iron loss:

  • Colon cancer may cause internal bleeding that leads to iron deficiency. Your doctor may check you for cancer by looking into your digestive tract with a flexible telescope (endoscopy). You may also have imaging studies to look for cancer. Endoscopy is recommended for all men and for women after menopause who have unexplained iron-deficiency anemia.

  • Digestive system diseases besides cancer also can cause bleeding and are common causes of iron deficiency. These include ulcer disease and inflammatory bowel diseases. Your doctor may use the same tests for cancer to look for these diseases.

  • If you donate blood frequently, you could be at risk for iron deficiency. People are allowed to donate blood every eight weeks, but giving blood more than three times a year can lead to iron deficiency.

Poor Absorption of Iron

You may have low iron if you have a digestive disease that interferes with your ability to absorb iron. Crohn’s disease, ulcerative colitis and celiac disease are common causes. Your doctor may do a blood test to check you for celiac disease if you have unexplained iron-deficiency anemia.

Other causes of decreased absorption:

  • Surgery that removes part of your digestive tract may lead to iron deficiency. This type of surgery may be done for cancer, other bowel diseases, and as part of weight loss surgery.

  • Children who drink more than 16 to 24 ounces of cow’s milk per day may be iron deficient because cow’s milk decreases iron absorption.

Not Enough Iron in Your Diet

Iron-deficiency anemia can also be due to a nutritional deficiency. If you eat a normal diet, you probably get enough iron from food. Foods highest in iron are meats and seafood. If you are a vegetarian, your diet could be a cause of iron deficiency. Another cause is having a poor diet or poor appetite. Being diagnosed with heart failure also greatly increases your risk of iron deficiency.

If you are in a high-risk group for iron deficiency, your doctor may do blood tests to rule out iron-deficiency anemia. Your doctor may also test you if you have symptoms of iron-deficiency anemia like fatigue, pale skin, shortness of breath, or headaches. Treatment may include looking for the cause and replacing your iron with iron supplements and diet changes.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2019 Sep 11

  1. Iron-Deficiency Anemia. American Society of Hematology.

  2. Iron Deficiency Anemia: Evaluation and Management. American Family Physician.

  3. Iron Dietary Supplement Fact Sheet. NIH, Office of Dietary Supplements.

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