Sickle cell anemia is one of a group of inherited disorders known as sickle cell disease. It affects the shape of red blood cells, which carry oxygen to all parts of the body.
Red blood cells are usually round and flexible, so they move easily through blood vessels. In sickle cell anemia, some red blood cells are shaped like sickles or crescent moons. These sickle cells also become rigid and sticky, which can slow or block blood flow.
There's no cure for most people with sickle cell anemia. Treatments can relieve pain and help prevent complications associated with the disease.
Sickle cell anemia
Signs and symptoms of sickle cell anemia usually appear around 6 months of age. They vary from person to person and may change over time. Signs and symptoms can include:
- Anemia. Sickle cells break apart easily and die. Red blood cells usually live for about 120 days before they need to be replaced. But sickle cells typically die in 10 to 20 days, leaving a shortage of red blood cells (anemia). Without enough red blood cells, the body can't get enough oxygen and this causes fatigue.
Episodes of pain. Periodic episodes of extreme pain, called pain crises, are a major symptom of sickle cell anemia. Pain develops when sickle-shaped red blood cells block blood flow through tiny blood vessels to your chest, abdomen and joints.
The pain varies in intensity and can last for a few hours to a few days. Some people have only a few pain crises a year. Others have a dozen or more a year. A severe pain crisis requires a hospital stay.
Some adolescents and adults with sickle cell anemia also have chronic pain, which can result from bone and joint damage, ulcers, and other causes.
- Swelling of hands and feet. The swelling is caused by sickle-shaped red blood cells blocking blood circulation in the hands and feet.
- Frequent infections. Sickle cells can damage the spleen, increasing vulnerability to infections. Infants and children with sickle cell anemia commonly receive vaccinations and antibiotics to prevent potentially life-threatening infections, such as pneumonia.
- Delayed growth or puberty. Red blood cells provide the body with the oxygen and nutrients needed for growth. A shortage of healthy red blood cells can slow growth in infants and children and delay puberty in teenagers.
- Vision problems. Tiny blood vessels that supply the eyes can become plugged with sickle cells. This can damage the retina — the portion of the eye that processes visual images — and lead to vision problems.
When to see a doctor
See your health care provider right away if you or your child has symptoms of sickle cell anemia. Because children with sickle cell anemia are prone to infections, which often start with a fever and can be life-threatening, seek prompt medical attention for a fever greater than 101.5 F (38.5 C).
Seek emergency care for symptoms of stroke, which include:
- One-sided paralysis or weakness in the face, arms or legs
- Difficulty walking or talking
- Sudden vision changes
- Unexplained numbness
- Severe headache
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Sickle cell anemia is caused by a change in the gene that tells the body to make the iron-rich compound in red blood cells called hemoglobin. Hemoglobin enables red blood cells to carry oxygen from the lungs throughout the body. The hemoglobin associated with sickle cell anemia causes red blood cells to become rigid, sticky and misshapen.
For a child to be affected, both mother and father must carry one copy of the sickle cell gene — also known as sickle cell trait — and pass both copies of the altered form to the child.
If only one parent passes the sickle cell gene to the child, that child will have the sickle cell trait. With one typical hemoglobin gene and one altered form of the gene, people with the sickle cell trait make both typical hemoglobin and sickle cell hemoglobin.
Their blood might contain some sickle cells, but they generally don't have symptoms. They're carriers of the disease, however, which means they can pass the gene to their children.
For a baby to be born with sickle cell anemia, both parents must carry a sickle cell gene. In the United States, sickle cell anemia most commonly affects people of African, Mediterranean and Middle Eastern descent.
Sickle cell anemia can lead to a host of complications, including:
- Stroke. Sickle cells can block blood flow to an area of the brain. Signs of stroke include seizures, weakness or numbness of the arms and legs, sudden speech difficulties, and loss of consciousness. If your child has any of these signs and symptoms, seek medical treatment immediately. A stroke can be fatal.
- Acute chest syndrome. A lung infection or sickle cells blocking blood vessels in the lungs can cause this life-threatening complication, resulting in chest pain, fever and difficulty breathing. It might require emergency medical treatment.
- Pulmonary hypertension. People with sickle cell anemia can develop high blood pressure in their lungs. This complication usually affects adults. Shortness of breath and fatigue are common symptoms of this condition, which can be fatal.
- Organ damage. Sickle cells that block blood flow to organs deprive the affected organs of blood and oxygen. In sickle cell anemia, blood is also chronically low in oxygen. This lack of oxygen-rich blood can damage nerves and organs, including kidneys, liver and spleen, and can be fatal.
- Splenic sequestration. A large number of sickle cells can get trapped in the spleen, causing it to enlarge and possibly causing belly pain on the left side of the body. This can be life-threatening. Parents of children with sickle cell anemia should learn to regularly feel their child's spleen for enlargement.
- Blindness. Sickle cells can block tiny blood vessels that supply the eyes. Over time, this can lead to blindness.
- Leg ulcers. Sickle cell anemia can cause painful open sores on the legs.
- Gallstones. The breakdown of red blood cells produces a substance called bilirubin. A high level of bilirubin in the body can lead to gallstones.
- Priapism. In this condition, men with sickle cell anemia can have painful, long-lasting erections. Sickle cells can block the blood vessels in the penis, which can lead to impotence over time.
- Deep vein thrombosis. Sickling of red cells can cause blood clots, increasing the risk of a clot lodging in a deep vein (deep vein thrombosis) or a lung (pulmonary embolism). Either can cause serious illness or even death.
- Pregnancy complications. Sickle cell anemia can increase the risk of high blood pressure and blood clots during pregnancy. It can also increase the risk of miscarriage, premature birth and having low birth weight babies.
If you carry the sickle cell trait, seeing a genetic counselor before trying to conceive can help you understand your risk of having a child with sickle cell anemia. A genetic counselor can also explain possible treatments, preventive measures and reproductive options.
Mar 09, 2022
- Sickle cell disease. National Heart, Lung, and Blood Institute. https://www.nhlbi.nih.gov/health-topics/sickle-cell-disease. Accessed Oct. 23, 2021.
- Field JJ, et al. Overview of the management and prognosis of sickle cell disease. https://www.uptodate.com/contents/search. Accessed Oct. 21, 2021.
- AskMayoExpert. Sickle cell disease. Mayo Clinic; 2021.
- Sickle cell disease (SCD). Centers for Disease Control and Prevention. https://www.cdc.gov/ncbddd/sicklecell/index.html. Accessed Oct. 23, 2021.
- Onimoe G, et al. Sickle cell disease: A primary care update. Cleveland Clinic Journal of Medicine. 2020; doi:10.3949/ccjm.87a.18051.