Diagnosing Hemolytic Anemia

Hemolytic anemia is a form of anemia due to hemolysis, the abnormal breakdown of red blood cells (RBCs), either in the blood vessels (intravascular hemolysis) or elsewhere in the human body (extravascular)Normally, red blood cells last for about 120 days in the body. In hemolytic anemia, red blood cells in the blood are destroyed earlier than normal.

Specialists Involved

Primary care doctors, such as a family doctor or pediatrician, may help diagnose and treat hemolytic anemia. Your primary care doctor also may refer you to a hematologist. This is a doctor who specializes in diagnosing and treating blood diseases and disorders.

Doctors and clinics that specialize in treating inherited blood disorders, such as sickle cell anemia and thalassemias, also may be involved.

If your hemolytic anemia is inherited, you may want to consult a genetic counselor. A counselor can help you understand your risk of having a child who has the condition. He or she also can explain the choices that are available to you.

Medical and Family Histories

To find the cause and severity of hemolytic anemia, your doctor may ask detailed questions about your symptoms, personal medical history, and your family medical history.

He or she may ask whether:

• You or anyone in your family has had problems with anemia
• You've recently had any illnesses or medical conditions
• You take any medicines, and which ones
• You've been exposed to certain chemicals or substances
• You have an artificial heart valve or other medical device that could damage your red blood cells

Physical Exam

Your doctor will do a physical exam to check for signs of hemolytic anemia. He or she will try to find out how severe the condition is and what's causing it.

The exam may include:

• Checking for jaundice (a yellowish color of the skin or whites of the eyes)
• Listening to your heart for rapid or irregular heartbeats
• Listening for rapid or uneven breathing
• Feeling your abdomen to check the size of your spleen
• Doing a pelvic and rectal exam to check for internal bleeding

Diagnostic Tests and Procedures

Many tests are used to diagnose hemolytic anemia. These tests can help confirm a diagnosis, look for a cause, and find out how severe the condition is.

Complete Blood Count

Often, the first test used to diagnose anemia is a complete blood count (CBC). The CBC measures many parts of your blood.

This test checks your hemoglobin and hematocrit (hee-MAT-oh-crit) levels. Hemoglobin is an iron-rich protein in red blood cells that carries oxygen to the body. Hematocrit is a measure of how much space red blood cells take up in your blood. A low level of hemoglobin or hematocrit is a sign of anemia.

The normal range of these levels may vary in certain racial and ethnic populations. Your doctor can explain your test results to you.

The CBC also checks the number of red blood cells, white blood cells, and platelets in your blood. Abnormal results may be a sign of hemolytic anemia, a different blood disorder, an infection, or another condition.

Finally, the CBC looks at mean corpuscular (kor-PUS-kyu-lar) volume (MCV). MCV is a measure of the average size of your red blood cells. The results may be a clue as to the cause of your anemia.

Other Blood Tests

If the CBC results confirm that you have anemia, you may need other blood tests to find out what type of anemia you have and how severe it is.

Reticulocyte count. A reticulocyte (re-TIK-u-lo-site) count measures the number of young red blood cells in your blood. The test shows whether your bone marrow is making red blood cells at the correct rate.

People who have hemolytic anemia usually have high reticulocyte counts because their bone marrow is working hard to replace the destroyed red blood cells.

Peripheral smear. For this test, your doctor will look at your red blood cells through a microscope. Some types of hemolytic anemia change the normal shape of red blood cells.

Coombs' test. This test can show whether your body is making antibodies (proteins) to destroy red blood cells.

Haptoglobin, bilirubin, and liver function tests. When red blood cells break down, they release hemoglobin into the bloodstream. The hemoglobin combines with a chemical called haptoglobin. A low level of haptoglobin in the bloodstream is a sign of hemolytic anemia.

Hemoglobin is broken down into a compound called bilirubin. High levels of bilirubin in the bloodstream may be a sign of hemolytic anemia. High levels of this compound also occur with some liver and gallbladder diseases. Thus, you may need liver function tests to find out what's causing the high bilirubin levels.

Hemoglobin electrophoresis. This test looks at the different types of hemoglobin in your blood. It can help diagnose the type of anemia you have.

Testing for paroxysmal nocturnal hemoglobinuria (PNH). In PNH, the red blood cells are missing certain proteins. The test for PNH can detect red blood cells that are missing these proteins.

Osmotic fragility test. This test looks for red blood cells that are more fragile than normal. These cells may be a sign of hereditary spherocytosis (an inherited type of hemolytic anemia).

Testing for glucose-6-phosphate dehydrogenase (G6PD) deficiency. In G6PD deficiency, the red blood cells are missing an important enzyme called G6PD. The test for G6PD deficiency looks for this enzyme in a sample of blood.

Urine Test

A urine test will look for the presence of free hemoglobin (a protein that carries oxygen in the blood) and iron.

Bone Marrow Tests

Bone marrow tests show whether your bone marrow is healthy and making enough blood cells. The two bone marrow tests are aspiration (as-pi-RA-shun) and biopsy.

For a bone marrow aspiration, your doctor removes a small amount of fluid bone marrow through a needle. The sample is examined under a microscope to check for faulty cells.

A bone marrow biopsy may be done at the same time as an aspiration or afterward. For this test, your doctor removes a small amount of bone marrow tissue through a needle. The tissue is examined to check the number and type of cells in the bone marrow.

You may not need bone marrow tests if blood tests show what's causing your hemolytic anemia.

Tests for Other Causes of Anemia

Because anemia has many causes, you may have tests for conditions such as:

• Kidney failure
• Lead poisoning
• Vitamin or iron deficiency

Newborn Testing for Sickle Cell Anemia and G6PD Deficiency

All States mandate screening for sickle cell anemia as part of their newborn screening programs. Some States also mandate screening for G6PD deficiency. These inherited types of hemolytic anemia can be detected with routine blood tests.

Diagnosing these conditions as early as possible is important so that children can get proper treatment.