What is iron deficiency anemia?
Iron deficiency anemia means that your body doesn't have enough iron to make red blood cells.
Iron is important because it helps you get enough oxygen throughout your body. Your body uses iron to make hemoglobin. Hemoglobin is a part of your red blood cells. Hemoglobin carries oxygen through your body. If you do not have enough iron, your body makes fewer and smaller red blood cells. Then your body has less hemoglobin, and you cannot get enough oxygen.
Iron deficiency is the most common cause of anemia.
What causes iron deficiency anemia?
Iron deficiency anemia is caused by low levels of iron in the body. You might have low iron levels because you:
- Have heavy menstrual bleeding.
- Are not getting enough iron in food. This can happen in people who need a lot of iron, such as small children, teens, and pregnant women.
- Have bleeding inside your body. This bleeding may be caused by problems such as ulcers, hemorrhoids, or cancer. This bleeding can also happen with regular aspirin use. Bleeding inside the body is the most common cause of iron deficiency anemia in men and in women after menopause.
- Cannot absorb iron well in your body. This problem may occur if you have celiac disease or if you have had part of your stomach or small intestine removed.
What are the symptoms?
You may not notice the symptoms of anemia, because it develops slowly and the symptoms may be mild. In fact, you may not notice them until your anemia gets worse. As anemia gets worse, you may:
- Feel weak and tire out more easily.
- Feel dizzy.
- Be grumpy or cranky.
- Have headaches.
- Look very pale.
- Feel short of breath.
- Have trouble concentrating.
Babies and small children who have anemia may:
- Be fussy.
- Have a short attention span.
- Grow more slowly than normal.
- Develop skills, such as walking and talking, later than normal.
Anemia in children must be treated so that mental and behavior problems do not last long.
How is iron deficiency anemia diagnosed?
If you think you have anemia, see your doctor. Your doctor will do a physical exam and ask you questions about your medical history and your symptoms. Your doctor will take some of your blood to run tests. These tests may include a complete blood count to look at your red blood cells and an iron test that shows how much iron is in your blood.
Your doctor may also do tests to find out what is causing your anemia.
How is it treated?
Your doctor will probably have you take iron supplement pills and eat foods rich in iron to treat your anemia. Most people begin to feel better after a few days of taking iron pills. But do not stop taking the pills even if you feel better. You will need to keep taking the pills for several months to build up the iron in your body.
If your doctor finds an exact cause of your anemia, such as a bleeding ulcer, your doctor will also treat that problem.
If you think you have anemia, do not try to treat yourself. Do not take iron pills on your own without seeing your doctor first. If you take iron pills without talking with your doctor first, the pills may cause you to have too much iron in your blood, or even iron poisoning. Your low iron level may be caused by a serious problem, such as a bleeding ulcer or colon cancer. These other problems need different treatment than iron pills.
You can get the most benefit from iron pills if you take them with vitamin C or drink orange juice. Do not take your iron pills with milk, caffeine, foods with high fiber, or antacids.
Can you prevent iron deficiency anemia?
You can prevent anemia by eating foods that contain iron every day. Iron-rich foods include meats, vegetables, and whole grains such as iron-fortified cereals.
You can prevent anemia in babies and children by following recommendations for feeding infants and making sure babies and children get enough iron.
If you are pregnant, you can prevent anemia by taking prenatal vitamins. Your doctor will give you prenatal vitamins that include iron. Your doctor will also test your blood to see if you are anemic. If you are anemic, you will take a higher-dose iron pill.
Mild iron deficiency anemia may not cause noticeable symptoms. If anemia is severe, symptoms may include:
- Weakness, fatigue, or lack of stamina.
- Shortness of breath during exercise.
- Trouble concentrating.
- Pale skin.
- Craving substances that are not food (pica). In particular, a craving for ice can be a sign of iron deficiency anemia.
Other signs may include:
- Rapid heartbeat.
- Brittle fingernails and toenails.
- Cracked lips.
- Smooth, sore tongue.
- Muscle pain during exercise.
- Trouble swallowing.
Babies and small children with iron deficiency anemia may not grow as expected and may have delays in skills such as walking and talking. Children may be irritable and have a short attention span. These problems usually go away when the deficiency is treated. If it is not treated, mental and behavior problems may be permanent.
Exams and Tests
If your doctor suspects iron deficiency anemia, he or she will do a physical exam and ask about your symptoms and your medical history. Your doctor will want to know about:
- Any medicines that you are taking.
- Your eating habits.
- Any current or past conditions or diseases that you or a close family member has had.
- Your history of pregnancy, menstruation, or other sources of bleeding.
Your doctor will recommend tests to check for low iron levels and anemia. Possible tests include:
- A complete blood count (CBC), to look at the shape, color, number, and size of your blood cells.
- Iron tests, which measure the amount of iron in your blood, to help determine the type and severity of anemia.
- Reticulocyte count, to help determine the cause of anemia. Reticulocytes are immature red blood cells produced by bone marrow and released into the bloodstream. Levels of reticulocytes are lower in iron deficiency anemia.
- A ferritin level test, which reflects how much iron may be stored in the body. Abnormally low ferritin levels may point to iron deficiency anemia. This is one of the first tests to be abnormal when you have iron deficiency.
If your doctor suspects that bleeding in your stomach or intestines is causing your anemia, you will have tests to determine the cause of the bleeding. These may include:
- A fecal occult blood test (FOBT), which looks for blood in stool samples.
- A colonoscopy. This test inspects the entire large intestine (colon) using a long, flexible, lighted viewing scope to look for polyps or other sources of bleeding.
- An upper gastrointestinal (GI) endoscopy. This test, which uses a thin, flexible, lighted viewing instrument, can help identify stomach ulcers or other causes of irritation or bleeding.
- Video capsule endoscopy. For this test, you swallow a capsule that contains a tiny camera. As the capsule travels through your system, the camera takes pictures of your small intestine that can show where bleeding is occurring.
- X-ray tests such as an upper GI series or barium enema.
If blood tests don't find the problem, you may need a test called a bone marrow aspiration. Bone marrow aspiration removes a small amount of bone marrow fluid through a needle inserted into the bone. Because iron is stored in the bone marrow, this test can provide a good idea of how much iron is in the body. But bone marrow aspirations are not done very often.
Treatment for iron deficiency anemia focuses on increasing your iron stores so they reach normal levels and identifying and controlling any conditions that caused the anemia. If your anemia is caused by:
- A disease or condition, such as bleeding in your stomach, your doctor will take steps to correct the problem.
- Not having enough iron in your diet or not being able to absorb iron, your doctor will work with you to develop a plan to increase your iron levels.
Taking iron supplement pills and getting enough iron in your food will correct most cases of iron deficiency anemia. You usually take iron pills 1 to 3 times a day. To get the most benefit from the pills, take them with vitamin C (ascorbic acid) pills or orange juice. Vitamin C helps your body absorb more iron.
Most people start to feel better within a few days of beginning treatment. Even though you feel better, you will need to keep taking the pills for several months to build up your iron stores. Sometimes it takes up to 6 months of treatment with iron supplements before iron levels return to normal.
You may need to get iron through an IV if you have problems with the iron pills or if your body doesn't absorb enough iron from food or iron pills.
If your anemia is severe, your doctor may give you a blood transfusion to correct your anemia quickly and then have you start on iron supplement pills and a diet high in iron.
To watch your condition, your doctor will use blood tests, such as:
- A complete blood count (CBC), to look at the shape, color, number, and size of your blood cells.
- Iron tests, which measure the amount of iron in your blood.
- A reticulocyte count, to see how well treatment is working. Reticulocytes are immature red blood cells produced by the bone marrow and released into the bloodstream. When reticulocyte counts increase, it usually means that iron replacement treatment is effective.
- A ferritin level test, which reflects how much iron may be stored in the body.
Usually, people can eliminate iron deficiency anemia by taking iron as pills and adding iron in their diet. If your anemia is not corrected with these treatments, your doctor might do more testing to look for other causes of your anemia, such as new bleeding or difficulty absorbing iron from pills. These tests may be the same as those initially used to diagnose your anemia.
What to think about
If you suspect you have iron deficiency anemia, do not take iron pills without consulting your doctor. Taking iron pills could delay the diagnosis of a serious problem such as colorectal cancer or a bleeding ulcer.
If the anemia is not due to iron deficiency, taking iron pills will not relieve the anemia and could cause poisoning (iron toxicity). It could also cause an iron overload condition called hemochromatosis, especially in people who have a genetic tendency toward storing too much iron in their bodies.
In some people, iron pills cause stomach discomfort, nausea, diarrhea, constipation, and black stool. Iron is best absorbed if taken on an empty stomach. But if you are having stomach problems, you may need to take the pills with food. Do not take iron pills with milk, caffeinated drinks, or antacids. If the side effects of your iron pills make you feel too sick, talk to your doctor. He or she may know of another type of iron pill you can take.
If you get iron through an IV, there is a risk of an allergic reaction.
If you have iron deficiency anemia, talk with your doctor about taking iron supplement pills and getting enough iron in your food each day. Iron-rich foods include meats, vegetables, and whole grains such as iron-fortified cereals.
To get the most benefit from your iron pills and the iron content of your food:
- Take vitamin C (ascorbic acid) or drink orange juice with your pills.
- Steam vegetables to help them retain their iron content.
Do not take your iron pills:
- Within 2 hours of taking antacids or tetracycline (an antibiotic).
- With certain foods, chemicals, and nutrients. These include:
- Tea, coffee, chocolate, and other food or beverages high in caffeine.
- Milk and other calcium-rich foods or supplements.
- High-fiber foods, such as bran, whole grains, nuts, and raw green vegetables.
In some people, iron supplements can cause stomach discomfort, nausea, diarrhea, constipation, and black stool. Iron is best absorbed if taken on an empty stomach. But if you are having stomach problems, you may need to take the pills with food. If the side effects of your iron pills make you feel too sick, talk to your doctor. He or she may know of another type of iron pill you can take.
If you think you have anemia, do not take iron pills without talking with your doctor. If the iron loss is from intestinal bleeding, taking iron pills may delay the diagnosis of a serious problem such as a bleeding ulcer or colon cancer. If the anemia is not due to iron deficiency, taking iron pills will not relieve the anemia and may cause poisoning (iron toxicity) or iron overload (hemochromatosis).
Keep iron tablets out of the reach of small children. Iron poisoning can be very dangerous.
Preventing iron deficiency
You can prevent anemia in babies and children by following recommendations for feeding infants and by making sure babies and children get enough iron.
If you are pregnant, your doctor will test your iron level at your first prenatal visit, and he or she will give you prenatal vitamins that include iron (30 mg a day). If you are anemic, your doctor will give you a higher-dose pill to take.
Other Works Consulted
- American Academy of Pediatrics (2010). Diagnosis and prevention of iron deficiency and iron-deficiency anemia in infants and young children (0–3 years of age). Pediatrics, 126(5): 1040–1050. Available online: http://pediatrics.aappublications.org/cgi/content/full/126/5/1040.
- Hillman RS, et al. (2011). Iron-deficiency anemia. In RS Hillman et al., eds., Hematology in Clinical Practice, 5th ed., pp. 53–64. New York: McGraw-Hill.
- Paulman P (2015). Iron deficiency. In ET Bope et al., eds., Conn's Current Therapy 2015, pp. 857–859. Philadelphia: Saunders.
- U.S. Preventive Services Task Force (2006). Screening and supplementation for iron deficiency anemia. Available online: http://www.uspreventiveservicestaskforce.org/uspstf/uspsiron.htm.
Current as of: November 8, 2019
Author: Healthwise Staff
E. Gregory Thompson MD - Internal Medicine
Adam Husney MD - Family Medicine
Martin J. Gabica MD - Family Medicine
Kathleen Romito MD - Family Medicine
Caroline S. Rhoads MD - Internal Medicine