To understand anemia (say: uh-nee-mee-uh), it helps to know a little bit about breathing. Have you ever tried to hold your breath? At first, you feel fine. After a short time, though, you need to take a breath. That's because when we breathe, our lungs take in oxygen (say: ok-sih-jen) from the air. We need oxygen to live.

We also need a way to get the oxygen from the lungs to the rest of the body. Blood flows like a river through every part of the body. The blood carries the oxygen, but the oxygen needs something to hang on to. It needs a boat — and the boats that carry oxygen are red blood cells.

Red blood cells (or RBCS, for short) are made inside the bones in the soft, spongy area called the bone marrow (say: mar-o). So every time you take a breath, you breathe in oxygen. And your RBCs carry oxygen to every cell in your body.

What Is Anemia?

Anemia occurs when a person doesn't have the normal amount of red blood cells or if the person is low on hemoglobin (say: hee-muh-glow-bin). Hemoglobin, a protein, is an important part of RBCs because it gives the oxygen something to stick to.

A kid who has anemia may not know it because he or she may not have any symptoms. Looking pale can be a sign of anemia because there is less blood flowing through the blood vessels in the skin. A fast heartbeat can be another sign of anemia, because when you don't have as many RBCs, the heart has to work harder to get the same amount of blood and oxygen to the body. If anemia worsens, a kid who was once very active may become worn out quickly. He or she may feel weak or tired.

Why Do Kids Get Anemia?

The bone marrow in a person's body makes new red blood cells to replace the old ones that die off after about 120 days.

A person may get anemia if:

• not enough RBCs are made
• too many RBCs are destroyed
• too many RBCs are lost (from bleeding)

Not enough being made: There are several reasons why the body might not make enough red blood cells, but often it's because someone isn't getting enough iron. Iron is a nutrient found in meat, dried beans, and green leafy vegetables. Without iron, the body can't make hemoglobin, the oxygen-carrying part of a red blood cell.

Besides iron, your body needs the vitamins B12 and folic acid to make RBCs. You get these vitamins in the foods you eat. Vitamin B12 is found in animal products, so vegetarians who don't eat meat, eggs, or dairy products have to look for other ways to get enough of this important vitamin. Folic acid is found in a variety of foods, such as citrus fruits, green vegetables, and fortified cereals.

Anemia also can develop if the bone marrow is not working properly. This may be because of an infection or a chronic illness, such as arthritis or kidney disease. In rare cases, someone might be born without the ability to make enough red blood cells. Certain medications like chemotherapy for cancer can keep the bone marrow from being able to make enough RBCs.

Too many being destroyed: If the life of a red blood cell is cut short for any reason, the bone marrow may not be able to keep up with the increased demand for new ones. One reason RBCs get destroyed is because their shape changes. If you looked at them through a microscope, you would see that they are round and flattened. That's a good shape for moving through tight spaces as blood circulates around the body.

If the shape changes, as is the case in sickle cell anemia, the red blood cells can get stuck and break. Sickle cells are curved like crescent moons. This shape makes it hard for them to move throughout the body. Sickle cell anemia is one of many genetic conditions that can shorten the life span of RBCs. Certain medications, infections, and chronic diseases also may cause this type of anemia.

Too much lost: When you lose a little blood, like when you cut yourself or have a nosebleed, your bone marrow is able to make more blood so you don't develop anemia. But if you lose a lot of blood, which may happen in a serious accident, your bone marrow might not be able to replace the red blood cells quickly enough.

If someone loses a little blood over a long period of time, it can also lead to anemia by losing more iron in the lost blood than is taken into the body by food you eat. Without enough iron in the body, the bone marrow can't make enough RBCs. This can happen in girls who have heavy menstrual periods, especially if they don't get enough iron in their diets, or in people who have inflammatory bowel disease (IBD).

What Do Doctors Do?

When you see the doctor, he or she will examine you and ask questions about how you have been feeling, what you eat, and if you are taking any medicines. If a doctor thinks a kid has anemia, he or she can order a simple blood test called a hematocrit (say: hih-mah-tuh-krit).

The blood sample then can be studied in the laboratory where the number of RBCs can be counted, the amount of hemoglobin can be measured, and the size and shape of the cells can be examined. A doctor may order additional tests, depending on what he or she suspects is the problem.

How Is Anemia Treated?

The treatment of anemia depends on the cause. In kids, the most common cause of anemia is not getting enough iron in their diets. Some kids may need to take medicine containing iron to help their bodies make more red blood cells. It is also important to eat more foods that are rich in iron, like meat, enriched grains and cereals, dried beans, and tofu.

If the anemia is caused by an infection, usually the anemia will go away when the infection is treated and the body gets healthy again. For some other types of anemia, the kid may need to see a specialist and have additional tests before treatment can start.

Whatever the cause, someone with severe anemia may need a blood transfusion. A transfusion means that donated blood, which is stored at a place called a blood bank, is given through tube in a vein. This may sound a little scary, but millions of kids and adults have blood transfusions every year. Except for inserting the tube, they don't hurt. And getting a blood transfusion is the fastest way to get blood to deliver oxygen to all the cells in the body.

Kids who have anemia may have to take it easy for a while. But once their bodies start making enough red blood cells, oxygen can reach all their tissues again, and they'll get some of that kid energy back!

Reviewed by: Robin Miller, MD
Date reviewed: September 2012