How Is Iron-Deficiency Anemia Diagnosed?

Iron-deficiency anemia is diagnosed using a person's medical history, a physical exam, and diagnostic tests and procedures. A doctor can use these methods to determine how severe the anemia is, its cause, and appropriate treatment. Mild to moderate anemia may have no signs or symptoms. In fact, anemia is often discovered unexpectedly on screening tests and when doctors are checking for other problems.

Specialists Involved

Primary care doctors often diagnose and treat iron-deficiency anemia. These doctors include pediatricians, family doctors, obstetricians, or internal medicine specialists. Other doctors may be consulted, such as experts on diseases of the blood (hematologists) or experts on diseases of the digestive system (gastroenterologists).

Medical and Family History

To find the cause of the anemia and how severe it is, the doctor may ask detailed questions about symptoms (see the What Are the Signs and Symptoms of Iron-Deficiency Anemia? section). The doctor may ask whether the person or a family member has ever had problems with anemia. The doctor will ask about things that may cause anemia, including illnesses, conditions (such as pregnancy), and medicines. The doctor also may ask about the person's diet and eating habits.

Physical Exam

A physical exam may include:

• Checking for pale or yellowish skin, gums, or nail beds
• Listening to the heart for a rapid or irregular heartbeat
• Listening to the lungs for rapid or uneven breathing
• Feeling the abdomen to check the size of the liver and spleen
• Checking for signs of bleeding, including a pelvic and rectal exam (these areas are common sources of blood loss)

The doctor also will order a number of tests or procedures to be sure about the type of anemia and how severe it is.

Diagnostic Tests and Procedures

Your doctor may order various tests or procedures to determine the type and severity of anemia you have. Usually, the first test used to diagnose anemia is a complete blood count (CBC). The CBC tells a number of things about a person's blood, including:

• The hemoglobin level. Hemoglobin is the iron-rich protein in red blood cells that carries oxygen through the body. The normal range of hemoglobin levels for the general population is 11.1-15.0 g/dL. A low hemoglobin level means a person has anemia.
• The hematocrit (hee-MAT-oh-crit) level. The hematocrit level measures how much of the blood is made up of red blood cells. The normal range for hematocrit levels for the general population is 32-43 percent. A low hematocrit level is another sign of anemia.

The normal range of these levels may be lower in certain racial and ethnic populations. Your doctor can explain your individual test results.

The CBC also checks:

• The numbers of red blood cells. Too few red blood cells means a person has anemia. A low number of red blood cells is usually seen with either a low hemoglobin or a low hematocrit level, or both.
• The numbers of white blood cells. White blood cells are involved in fighting infection.
• The number of platelets in the blood. Platelets are small cells that are involved in blood clotting.
• Red blood cell size. The mean cell volume measures the average size (volume) of red blood cells. In iron-deficiency anemia, the red blood cells are often smaller than normal.

If the CBC results confirm that you have anemia, your doctor may order additional tests to determine the cause, severity, and correct treatment for your condition. For example, the doctor may order a reticulocyte (re-TIK-u-lo-site) count. Reticulocytes are young red blood cells. This test measures the number of new red blood cells in your blood. The reticulocyte test is used to determine whether your bone marrow is producing red blood cells at the proper rate.

Tests That Measure Iron Levels in the Body

Iron is needed to make hemoglobin-the protein in red blood cells that gives them their color and carries oxygen. Several tests can be used to check the level of iron in the blood and in the body:

• Serum iron. This test measures the amount of iron in the blood. The level of iron in the blood can be normal even when the total amount of iron in the body is low. For this reason, other iron tests are done.
• Serum ferritin. Ferritin is a protein that helps store iron in the body. Results of this test give doctors a good idea of how much of the body's stored iron has been used up.
• Transferrin level or total iron-binding capacity. Transferrin is a protein that carries iron in the blood. Total iron-binding capacity measures how much of the transferrin in the blood is not carrying iron. People with iron-deficiency anemia have a high level of transferrin that has no iron.
• Other blood tests. Other tests the doctor may order include tests that check hormone levels, especially the thyroid hormone. Blood tests also may be ordered to check the level of a chemical used by the body to make hemoglobin. It is called erythrocyte protoporphyrin.

Tests That Diagnose Gastrointestinal Bleeding

If your doctor suspects anemia because of internal bleeding in the stomach or intestines, several tests may be used to discover the source of the bleeding.

One of the first tests ordered is the fecal occult blood test. This test checks the stool for signs of blood. It can detect even small amounts of bleeding anywhere in the intestines. If blood is found in the stool, further tests may be used to find the source of the bleeding, including:

• Colonoscopy. In this test, a thin, flexible tube attached to a video camera is used to examine the rectum and colon for sources of bleeding.
• Upper GI endoscopy. In this test, a thin, flexible tube attached to a video camera is used to examine the stomach and upper intestines. The doctor looks for signs of bleeding.
• Pelvic ultrasound. This test uses sound waves to look at the uterus and other pelvic organs. It checks for causes of heavy vaginal bleeding, such as fibroids.