Hemolytic anemia (HEE-moh-lit-ick uh-NEE-me-uh) is a condition in which red blood cells are destroyed and removed from the bloodstream before their normal lifespan is up.
Red blood cells are disc-shaped and look like doughnuts without holes in the center. These cells carry oxygen and remove carbon dioxide (a waste product) from your body. Red blood cells are made in the bone marrow—a sponge-like tissue inside the bones. They live for about 120 days in the bloodstream and then die.
White blood cells and platelets (PLATE-lets) also are made in the bone marrow. White blood cells help fight infection. Platelets stick together to seal small cuts or breaks on blood vessel walls and stop bleeding.
When blood cells die, the body's bone marrow makes more blood cells to replace them. However, in hemolytic anemia, the bone marrow can't make red blood cells fast enough to meet the body's needs.
Hemolytic anemia can lead to various health problems, such as fatigue (tiredness), pain, arrhythmias (ah-RITH-me-ahs), an enlarged heart, and heart failure.
Hemolytic anemia is a type of anemia. The term "anemia" usually refers to a condition in which your blood has a lower than normal number of red blood cells. This condition also can occur if your red blood cells don't contain enough hemoglobin (HEE-muh-glow-bin). This iron-rich protein helps carry oxygen to your body.
Anemia has three main causes: blood loss, lack of red blood cell production, or high rates of red blood cell destruction.
Hemolytic anemia is due to high rates of red blood cell destruction. A number of diseases, conditions, and factors can cause the body to destroy its red blood cells.
These causes can be inherited or acquired. "Inherited" means your parents passed the gene for the condition on to you. "Acquired" means you aren't born with the condition, but you develop it. Sometimes the cause of hemolytic anemia isn't known.
There are many types of hemolytic anemia. Treatment and outlook depend on what type you have and how severe it is. The condition can develop suddenly or slowly. Symptoms can range from mild to severe.
Hemolytic anemia often can be successfully treated or controlled. Mild hemolytic anemia may need no treatment at all. Severe hemolytic anemia requires prompt and proper treatment or it may be fatal.
Inherited forms of hemolytic anemia are lifelong conditions that may require ongoing treatment. Acquired forms of anemia may go away if the cause of the condition is found and corrected.
Types of Hemolytic Anemia
There are many types of hemolytic anemia. The condition can be inherited or acquired. "Inherited" means your parents passed the gene for the condition on to you. "Acquired" means you aren't born with the condition, but you develop it due to another disease, condition, or factor.
Inherited Hemolytic Anemias
With inherited hemolytic anemias, one or more of the genes that control red blood cell production are faulty. The defects may involve the hemoglobin, cell membrane, or enzymes that maintain healthy red blood cells.
The abnormal cells may be fragile and break down while moving through the bloodstream. If this happens, an organ called the spleen may remove the cell debris from the bloodstream.
Sickle Cell Anemia
Sickle cell anemia is a serious, inherited disease. In this disease, the body makes abnormal hemoglobin. This causes the red blood cells to have a sickle, or "C," shape.
Sickle cells don't last as long as healthy red blood cells. They usually die after only about 10 to 20 days. The bone marrow can't make new red blood cells fast enough to replace the dying ones.
Sickle cell anemia mainly affects people of African descent.
Thalassemias are inherited blood disorders in which the body doesn't make enough of certain types of hemoglobin. This causes the body to make fewer healthy red blood cells than normal.
Thalassemias most often affect people of Southeast Asian, Indian, Chinese, Filipino, Mediterranean, or African origin or descent.
In this condition, a defect in the surface membrane (the outer covering) of red blood cells causes them to take on a sphere, or ball-like, shape. These blood cells have a lifespan that's shorter than normal.
Hereditary spherocytosis (SFER-o-si-to-sis) is the most common cause of hemolytic anemia among people of Northern European descent.
Hereditary Elliptocytosis (Ovalocytosis)
This condition also involves a problem with the cell membrane. With this condition, the red blood cells are elliptic (oval) in shape. They aren't as flexible as normal red blood cells, and they have a shorter lifespan.
Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency
In G6PD deficiency, the red blood cells are missing an important enzyme called G6PD. G6PD is part of the normal chemistry inside red blood cells.
In G6PD deficiency, if red blood cells come into contact with certain substances in the bloodstream, the missing enzyme causes the cells to rupture and die.
A number of factors can trigger the breakdown of the red blood cells. Examples include taking sulfa or antimalarial medicines; being exposed to naphthalene, a substance found in some moth balls; eating fava beans; or having an infection.
G6PD deficiency mostly affects males of African or Mediterranean descent. It affects about 1 in 10 African American males.
Pyruvate Kinase Deficiency
With this condition, your body is missing an enzyme called pyruvate kinase. Not having enough of this enzyme causes red blood cells to break down easily.
This disorder is more common among the Amish than other groups.
Acquired Hemolytic Anemias
With acquired hemolytic anemias, your red blood cells may be normal. However, some other disease or factor causes the body to destroy red blood cells and remove them from the bloodstream.
The destruction of the red blood cells occurs in the bloodstream or, more commonly, in the spleen.
Immune Hemolytic Anemia
In immune hemolytic anemia, your immune system destroys your red blood cells. The three main types of immune hemolytic anemia are: autoimmune, alloimmune, and drug-induced.
Autoimmune hemolytic anemia (AIHA). In this condition, your immune system makes antibodies (proteins) that attack your red blood cells. Why this happens isn't known. AIHA accounts for half of all cases of hemolytic anemia. AIHA may come on very quickly and become serious. It's most common in people older than 40.
Having certain diseases or infections can raise your risk for AIHA. Examples include:
- Autoimmune diseases, such as lupus
- Chronic lymphocytic leukemia
- Non-Hodgkin's lymphoma and other blood cancers
- Epstein-Barr virus
- Mycoplasma pneumonia
In some types of AIHA, the antibodies made by the body are called warm antibodies. This means they're active (that is, they destroy red blood cells) at warm temperatures, such as body temperature.
In other types of AIHA, the body makes cold-reactive antibodies, which become active in colder temperatures. Cold-reactive antibodies can become active when parts of the body, such as the hands or feet, are exposed to temperatures lower than 32 to 50 degrees Fahrenheit (0 to 10 degrees Celsius).
Warm antibody AIHA is more common than cold-reactive antibody AIHA.
Alloimmune hemolytic anemia. This type of hemolytic anemia occurs if your body makes antibodies against red blood cells that you get from a blood transfusion. This can happen if the transfused blood is a different blood type than your blood.
This type of hemolytic anemia also can occur during pregnancy if there's a difference in blood type between the mother and the fetus. For more information, see the Diseases and Conditions Index Rh Incompatibility article.
Drug-induced hemolytic anemia. Certain medicines can cause a reaction that develops into hemolytic anemia. Some medicines, such as penicillin, bind to red blood cell surfaces and can cause antibodies to develop.
Other medicines cause hemolytic anemia in other ways. Examples of such medicines include acetaminophen; quinine and antimalarial medicines; anti-inflammatory medicines; and levodopa.
Mechanical Hemolytic Anemias
Physical damage to red blood cell membranes can cause them to break down faster than normal. Damage may be due to:
- Changes in the small blood vessels.
- An artificial heart valve or other device used in blood vessels.
- A heart-lung bypass machine, which may be used during open-heart surgery.
- Preeclampsia (pre-e-KLAMP-se-ah) or eclampsia. Preeclampsia is high blood pressure during pregnancy. Eclampsia, which follows preeclampsia, is a serious condition that causes seizures in pregnant women.
Blood cell damage also may occur in the limbs while participating in marathons or other strenuous activities.
Paroxysmal Nocturnal Hemoglobinuria
Paroxysmal nocturnal hemoglobinuria (PNH) is a disorder in which the red blood cells are abnormal due to a lack of certain proteins. The body destroys these cells more quickly than normal.
People who have PNH are at increased risk for blood clots in the veins and low levels of white blood cells and platelets.
Other Causes of Damage to Red Blood Cells
Certain infections and substances also can damage red blood cells and lead to hemolytic anemia. Examples include malaria and blackwater fever, tick-borne diseases, snake venom, and toxic chemicals.
What Causes Hemolytic Anemia?
The immediate cause of hemolytic anemia is the early destruction of red blood cells. This means that red blood cells are destroyed and removed from the bloodstream before their normal lifespan is up.
A number of diseases, conditions, and factors can cause the body to destroy its red blood cells. These causes can be inherited or acquired. Sometimes, the cause of hemolytic anemia isn't known.
For more information on specific causes of hemolytic anemia, see "Types of Hemolytic Anemia."
Inherited Hemolytic Anemias
In inherited hemolytic anemias, the genes that control how red blood cells are made are faulty. You can receive a faulty red blood cell gene from one or both of your parents.
Different types of faulty genes account for the different types of inherited hemolytic anemia. In each type of inherited hemolytic anemia, the body makes abnormal red blood cells.
The problem with the red blood cells may involve the hemoglobin, cell membrane, or enzymes that maintain healthy red blood cells.
The abnormal cells may be fragile and break down while moving through the bloodstream. If this happens, an organ called the spleen may remove the cell debris from the bloodstream.
Acquired Hemolytic Anemias
In acquired hemolytic anemias, the body makes normal red blood cells. However, some disease, condition, or factor destroys the cells too early. Examples include immune disorders, infections, and reactions to medicines or blood transfusions.
Who Is At Risk for Hemolytic Anemia?
Hemolytic anemia can affect people of all ages and races and both sexes.
Autoimmune hemolytic anemia is slightly more common in women older than 40. Glucose-6-phosphate dehydrogenase (G6PD) deficiency is more common among males.
Some types of hemolytic anemia are more likely to occur in certain populations than others. For example, sickle cell anemia mainly affects people of African descent. G6PD deficiency affects males of African or Mediterranean descent. About 1 in 10 African American men have G6PD deficiency.
What Are the Signs and Symptoms of Hemolytic Anemia?
Signs and symptoms will depend on the type of hemolytic anemia you have and how severe it is.
People who have mild hemolytic anemia often have no signs or symptoms. More severe hemolytic anemia may cause a number of signs and symptoms, and they may be serious.
Many of the signs and symptoms of hemolytic anemia apply to all types of anemia.
Signs and Symptoms of Anemia
The most common symptom of all types of anemia is fatigue (tiredness). This symptom is due to your body not having enough red blood cells to carry oxygen to its various parts.
A low red blood cell count also can cause shortness of breath; dizziness, especially when standing up; headache; coldness in your hands or feet; pale skin, gums, and nail beds; and chest pain.
A lack of red blood cells also means that your heart has to work harder to move oxygen-rich blood through your body. This can lead to arrhythmias, a heart murmur, an enlarged heart, or even heart failure.
Signs and Symptoms of Hemolytic Anemia
Jaundice refers to a yellowish color of the skin or whites of the eyes. When red blood cells die, they release hemoglobin into the bloodstream.
The hemoglobin is broken down into a compound called bilirubin, which gives the skin and eyes a yellowish color. Bilirubin also causes urine to be dark yellow or brown.
Pain in the Upper Abdomen
Pain in the upper abdomen may be due to gallstones or an enlarged spleen. High levels of bilirubin and cholesterol (from the breakdown of red blood cells) can form into stones in the gallbladder. These stones can be painful.
The spleen is an organ in the abdomen that helps fight infection and filters out old or damaged blood cells. In hemolytic anemia, the spleen may be enlarged, which can be painful.
Leg Ulcers and Pain
In people who have sickle cell anemia, the sickle-shaped cells can clog small blood vessels and block blood flow. This can cause leg sores and pain in different parts of the body.
A Severe Reaction to a Blood Transfusion
You may develop hemolytic anemia due to a blood transfusion. This can happen if the transfused blood is a different blood type than your blood.
Signs and symptoms of a severe reaction to this procedure include fever, chills, low blood pressure, and shock (a life-threatening condition that occurs when the body isn't getting enough blood flow).
How Is Hemolytic Anemia Diagnosed?
Hemolytic anemia is diagnosed based on your medical and family histories, a physical exam, and the results from tests.
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 (blood disease specialist).
Doctors and clinics that specialize in treating inherited blood disorders, such as sickle cell anemia and thalassemias, also may be involved.
If you have an inherited form of hemolytic anemia, you may want to consult a genetic counselor. A counselor can help you understand your risk of having a child who has the condition and the choices that are available to you.
Medical and Family Histories
To find out 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
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 abnormal 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
A number of 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 hemolytic anemia is a complete blood count (CBC). The CBC measures many different 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 the 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 blood may be a sign of hemolytic anemia. High levels of this compound also occur with some liver and gallbladder diseases. As a result, 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.
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.
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 types 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. Most States also mandate screening for G6PD deficiency. These inherited types of hemolytic anemia can be detected with routine blood tests.
It's important to diagnose these conditions as early as possible so that children can get proper treatment.
How Is Hemolytic Anemia Treated?
Treatments for hemolytic anemia include blood transfusions, medicines, plasmapheresis, surgery, blood and marrow stem cell transplants, and lifestyle changes.
People who have mild hemolytic anemia may not need treatment, as long as the condition doesn't worsen. People who have severe hemolytic anemia usually need ongoing treatment. Severe hemolytic anemia can be fatal if it's not properly treated.
Goals of Treatment
The goals of treating hemolytic anemia include:
- Reducing or stopping the destruction of red blood cells
- Increasing the red blood cell count to an acceptable level
- Treating the underlying cause of the condition
Treatment will depend on the type, cause, and severity of the hemolytic anemia you have. Your doctor also will consider your age, overall health, and medical history.
If you have an inherited form of hemolytic anemia, it's a lifelong condition that may require ongoing treatment. If you have an acquired form of hemolytic anemia, it may go away once its cause can be found and corrected.
Blood transfusions are used to treat severe or life-threatening hemolytic anemia.
A blood transfusion is a common procedure in which blood is given to you through an intravenous (IV) line in one of your blood vessels. Transfusions require careful matching of donated blood with the recipient's blood.
Medicines can improve some types of hemolytic anemia, especially autoimmune hemolytic anemia (AIHA). Corticosteroid medicines, such as prednisone, are used to limit or prevent your immune system from making antibodies against red blood cells.
If you don't respond to corticosteroids, your doctor may prescribe other medicines to suppress your immune system.
If you have severe sickle cell anemia, your doctor may recommend a medicine called hydroxyurea. This medicine reduces the number of red blood cells with abnormal hemoglobin that your body makes. It also promotes the production of red blood cells with normal hemoglobin.
Plasmapheresis is a procedure that removes antibodies from the blood. For this procedure, blood is taken from your body using a needle inserted into a vein.
The plasma, which contains the antibodies, is separated from the rest of the blood. Then, plasma from a donor and the rest of the blood is put back in your body.
This treatment may help if other treatments for immune hemolytic anemia don't work.
Some people who have hemolytic anemia may need surgery to remove their spleens. The spleen is an organ in the abdomen. A healthy spleen helps fight infection and filters out old or damaged blood cells.
An enlarged or diseased spleen may remove more red blood cells than normal, causing anemia. Removing the spleen can stop or reduce high rates of red blood cell destruction.
Blood and Marrow Stem Cell Transplant
In some types of hemolytic anemia, such as thalassemias, the bone marrow doesn't make enough healthy red blood cells. The red blood cells it does make may be destroyed before their normal lifespan is over. Blood and marrow stem cell transplants may be used to treat these types of hemolytic anemia.
A blood and marrow stem cell transplant replaces damaged stem cells with healthy ones from another person (a donor).
During the transplant, which is like a blood transfusion, you get donated stem cells through a tube placed in a vein. Once the stem cells are in your body, they travel to your bone marrow and begin making new blood cells.
If you have AIHA with cold-reactive antibodies, try to avoid cold temperatures. This can help prevent the breakdown of red blood cells. It's very important to protect your fingers, toes, and ears from the cold.
To protect yourself, you can:
- Wear gloves or mittens when taking food out of the refrigerator or freezer.
- Wear a hat, scarf, and a coat with snug cuffs during cold weather.
- Turn down air conditioning or dress warmly while in an air-conditioned space.
- Warm up the car before driving in cold weather.
People born with glucose-6-phosphate dehydrogenase (G6PD) deficiency can avoid substances that may trigger anemia. For example, avoid fava beans, naphthalene (a substance found in some moth balls), and certain medicines (as your doctor advises).
How Can Hemolytic Anemia Be Prevented?
You can't prevent inherited types of hemolytic anemia. One exception is glucose-6-phosphate dehydrogenase (G6PD) deficiency.
If you're born with G6PD deficiency, you can avoid substances that may trigger the condition. For example, avoid fava beans, naphthalene (a substance found in some moth balls), and certain medicines (as your doctor advises).
Some types of acquired hemolytic anemia can be prevented. For example, reactions to blood transfusions, which can cause hemolytic anemia, can be prevented. This requires careful matching of blood types between the blood donor and the recipient.
Prompt and proper prenatal care can help you avoid the problems of Rh incompatibility. A difference in blood type between a pregnant woman and her fetus causes this condition. Rh incompatibility can lead to hemolytic anemia in a fetus or newborn.
Living With Hemolytic Anemia
Hemolytic anemia can be mild or severe. Inherited forms of hemolytic anemia are lifelong conditions and may require ongoing treatment. Acquired forms of the condition may go away if the cause is found and corrected.
If you have hemolytic anemia, it's important to take care of your health. See your doctor regularly and follow your treatment plan. Talk to your doctor about whether you should get a yearly flu shot and a pneumonia vaccine.
Ask your doctor about ways to reduce your chance of getting an infection. For example, you may want to:
- Stay away from people who are sick and avoid large crowds of people.
- Avoid certain kinds of foods that can expose you to bacteria, such as uncooked foods.
- Wash your hands often.
- Brush and floss your teeth and get regular dental care to reduce the risk of infection in your mouth and throat
You can take steps to stay healthy. Try to get plenty of rest.
If you have cold-reactive autoimmune hemolytic anemia, stay away from cold temperatures. During cold weather, wear a hat, scarf, and a warm coat. When taking cold food out of the refrigerator or freezer, wear gloves. Turn down air conditioning or dress warmly while in an air-conditioned space. Warm up the car before driving in cold weather.
If you have glucose-6-phosphate dehydrogenase (G6PD) deficiency, avoid substances that can trigger anemia. For example, avoid fava beans, naphthalene (a substance found in some moth balls), and certain medicines (as your doctor advises).
Talk to your doctor about what types and amounts of physical activity are safe for you. You may want to avoid certain sports or activities that could worsen your condition or lead to complications.
Hemolytic Anemia and Children
Parents of children who have hemolytic anemia usually want to learn as much as possible about the condition from their child's health care team.
You can be an active partner in caring for your child. Talk to your child's health care team about treatment, diet, and appropriate physical activities.
Learn the signs of worsening anemia and possible complications so you can contact your child's doctor.
You may want to educate family members, friends, and your child's classmates about hemolytic anemia. You also may want to tell your child's teachers or other caregivers about the condition. Let them know whether your child has any special limitations or restrictions.
Family members, friends, teachers, and caregivers can provide a network of support to help your child cope with his or her hemolytic anemia.
Allow teenagers to have input in decisions about their care. This encourages them to take an active role in their health care. Help them understand lifestyle restrictions and their medical needs so they can better cope with having hemolytic anemia.