How Is Hemolytic Anemia Diagnosed?

Hemolytic anemia is diagnosed using a combination of medical and family history, physical exam, and diagnostic tests.

Specialists Involved

Primary care doctors, such as a family doctor or pediatrician, may be involved in diagnosing and treating hemolytic anemia. Other kinds of doctors involved include:

• A hematologist (blood disease specialist)
• A cardiologist (heart specialist)

Doctors and clinics that specialize in treating inherited blood disorders, such as sickle cell anemia and thalassemia, may be involved. If you have an inherited form of hemolytic anemia, you may want to consult a genetics counselor.

Medical and Family History

To determine the cause and severity of hemolytic anemia, your doctor may ask detailed questions about your symptoms, personal medical history, and your family medical history. You may be asked whether you or anyone in your family has had problems with anemia in the past. Your doctor will want to know what illnesses or conditions you have had recently and what medicines you take.

You also may be asked whether you have been exposed to any drugs or chemicals or have an artificial heart valve or device that could damage red blood cells.

Physical Exam

Your doctor will perform a physical exam to determine how severe the anemia is and to check for possible causes. This exam may include:

• Checking for jaundice (yellowish skin and eyes)
• Listening to your heart for a rapid or abnormal heartbeat
• Listening for rapid or uneven breathing
• Feeling your abdomen to check the size of your liver and spleen
• Performing a pelvic and rectal exam to check for internal bleeding

Diagnostic Tests and Procedures

Your doctor may perform a number of tests, including the following:

Blood Tests

Complete blood count. 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 11-15 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 different in certain racial and ethnic populations. Your doctor can explain your individual test results.

The CBC also checks:

• The number 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.
• Red blood cell size. The mean cell volume measures the average size (volume) of red blood cells. Red blood cells can be normal sized, smaller, or larger, depending on the type of anemia.
• The number of white blood cells. White blood cells are involved in fighting infection.
• The number of platelets. Platelets are small cells that are involved in blood clotting.

Additional blood tests. If the CBC results confirm you have anemia, your doctor may order additional blood tests to determine the type and cause of the anemia. Some of the tests that can be used in the diagnosis of hemolytic anemia include:

• Reticulocyte (re-TIK-u-lo-site) count. Reticulocytes are young red blood cells. The reticulocyte count measures the rate at which the bone marrow is producing new red blood cells. Typically in hemolytic anemia, the reticulocyte count is higher than normal because the bone marrow is working overtime to replace the destroyed red blood cells.
• Peripheral smear. This test involves looking at the blood cells through a microscope. Some types of hemolytic anemia involve abnormally shaped red blood cells, which can be seen through a microscope.
• Coombs' test. The Coombs' test measures the presence of antibodies directed against red blood cells.
• Haptoglobin, bilirubin, and liver function tests. When red blood cells break down, they release their hemoglobin into the bloodstream. The hemoglobin combines with a chemical called haptoglobin. A low level of haptoglobin in the bloodstream is an indication of hemolytic anemia. Bilirubin comes from the breakdown of hemoglobin. High levels of bilirubin cause jaundice, a yellowish discoloration to the skin and eyes. High levels of bilirubin in the blood occur with the hemolysis of red blood cells, and also with some liver and gallbladder diseases. Liver function tests help to determine whether high bilirubin levels are from hemolytic anemia or liver/gallbladder disease.
• Hemoglobin electrophoresis. This test detects abnormal hemoglobin, which is the cause of some types of hemolytic anemia.
• Testing for paroxysmal nocturnal hemoglobinuria (PNH). In PNH, the red blood cells are missing certain proteins. The test for PNH looks for red blood cells that are missing these proteins.
• Osmotic fragility test. This test looks for abnormally fragile red blood cells, which are seen in hereditary spherocytosis.
• Testing for glucose-6-phosphate dehydrogenase deficiency (G6PD) deficiency. This test, called a rapid fluorescent spot test, detects evidence of G6PD enzyme activity in a sample of blood.

Bone Marrow Tests

In some cases, the doctor may want to examine the cells of the bone marrow under a microscope. A sample of bone marrow can be obtained with either a bone marrow biopsy or aspiration. A bone marrow biopsy is a minor surgical procedure to remove a small amount of bone marrow tissue. For a bone marrow aspiration, your doctor removes a small amount of bone marrow fluid through a needle.

Tests for Other Causes of Anemia

Because anemia has many causes, the doctor may order tests for conditions such as:

• Kidney failure
• Lead poisoning
• Low levels of vitamins, including vitamin B12, vitamin C, and folate
• Iron deficiency