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Diagnosing Anemia in Children

Anemia is a common condition in children. About 20 percent of children in the U.S. will be diagnosed with anemia at some point by age 18. A child who is anemic does not have enough red blood cells or enough hemoglobin. Hemoglobin is a special type of protein that allows red blood cells to carry oxygen to other cells in the body.

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Anemia has three main causes: loss of red blood cells from bleeding; inability to make enough red blood cells; and a medical condition that causes the destruction of red blood cells.

In most cases, anemia can be diagnosed with a few simple blood tests. The American Academy of Pediatrics recommends that all infants be given a blood test to look for anemia at 6 months, 9 months, or 12 months of age. For older children, a blood test for anemia may be done during a child's routine physical examination.

Symptoms of anemia in children

Many children with anemia have no symptoms. That's why it's important for children to have routine blood tests to check for the condition. Some of the signs and symptoms that might make a doctor suspect anemia in a child include:

  • Pale skin

  • Irritability

  • Weakness

  • Dizziness

  • Sore tongue

  • Rapid heartbeat

  • Rapid breathing

  • Yellow skin color

Blood tests for diagnosing anemia

To get a blood sample, a health care provider will insert a needle into a vein, usually in the child's arm or hand. A tourniquet may be wrapped around the child's arm to help the health care worker locate a vein. Blood may be drawn up into a syringe or a test tube. In some cases, blood can be taken using a needle prick.

Blood tests may cause a little discomfort while the needle is inserted, and the needle may cause some bruising or swelling. After the blood is removed, the health care provider will remove the tourniquet, put pressure on the area, and apply an adhesive bandage. 

It's possible to have persistent bleeding, nerve damage, or infections from a blood test, but these risks are small. In most cases, a child will not need any special preparation or care after a blood test.

Most anemias in children can be diagnosed with these blood tests:

  • Hemoglobin and hematocrit. This is often the first screening test for anemia in children. It measures the amount of hemoglobin in the blood and the amount of red blood cells in the blood sample.

  • Complete blood count, or CBC. If hemoglobin or hematocrit is abnormal, a complete blood count may be done. This test adds important information about the blood, including the size of red blood cells (called the mean corpuscular volume, or MCV).

  • Peripheral smear. This test involves a smear of blood on a slide that is examined under a microscope. By looking at a child's blood cells under a microscope, a laboratory specialist may be able to diagnose a type of anemia that causes red cells to grow or develop abnormally.

  • Reticulocyte count. Reticulocytes are immature blood cells. A reticulocyte count measures the percentage of newly formed red blood cells in the child's blood sample. Anemia caused by not enough red blood cells being made results in a low reticulocyte count. Anemia caused by too many red blood cells being lost causes a high reticulocyte count.

Types of anemia in children

Once a doctor has evaluated the child's blood tests, the type of anemia can usually be determined and treatment can be started. Children's anemia can be classified by the size of their red blood cells:

  • Microcytic anemia. This means the child's red blood cells are smaller than normal. The most common cause of microcytic anemia is iron deficiency.

  • Normocytic anemia. This means the child's red blood cells are normal in size. Normocytic anemia has many causes and may require other special types of blood tests.

  • Macrocytic anemia. This means the child's red blood cells are larger than normal. This is the rarest type of anemia in children. It may be caused by vitamin B12 deficiency.

Treating anemia in children depends on the type of anemia and its cause. In some cases, treatment may require simply a change in diet or the use of diet supplements. In other cases, a blood transfusion or long-term treatment may be needed. Screening for anemia is an important part of caring for a child. Many problems caused by anemia can be prevented when anemia in children is diagnosed at an early stage. 

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