What is sickle cell disease?

Sickle cell disease (SCD) is an inherited blood disorder. That means it is passed down from a parent’s genes. It causes the body to make abnormal hemoglobin. Hemoglobin is the protein in red blood cells that carries oxygen to all parts of your body. When you have SCD, your body’s tissues and organs don’t get enough oxygen.

Healthy red blood cells are round and move easily all over the body. With SCD, the red blood cells are hard and sticky. They are shaped like the letter C (and like a farm tool called a sickle). These damaged red blood cells (sickle cells) clump together. They can’t move easily through the blood vessels. They get stuck in small blood vessels and block blood flow. This blockage stops the movement of healthy oxygen-rich blood. This blockage can cause pain. It can also damage major organs.

Sickle cells die sooner than healthy cells. Normally the spleen helps filter infections out of the blood. But sickle cells get stuck in this filter and die. Having fewer healthy red blood cells causes anemia. The sickle cells can also damage the spleen. You are then at greater risk for infections.

What causes sickle cell disease?

SCD is an inherited disease caused by a defect in a gene:

• You are born with SCD only if 2 genes are inherited—1 from each parent.

• If you have just 1 gene you are healthy, but you are a carrier of the disease. If 2 carriers have a child, there is a greater chance their child will have SCD.

• Parents who are each a carrier of a sickle cell gene have a 1 in 4 chance of having a child with SCD.

Who is at risk for sickle cell disease?

Having a family history of SCD increases your risk for the disease. SCD mainly affects people whose families came from Africa, Central America, South America, the Middle East, Asia, India, the Mediterranean, or Southern Europe. One in 365 Black babies in the U.S. is born with SCD. One in 13 Black babies in the U.S. carries the sickle cell gene.

What are the symptoms of sickle cell disease?

Each person’s symptoms may vary. They may be mild or severe. Symptoms may include:

• Anemia. This symptom is the most common one. Having fewer red blood cells causes anemia. Severe anemia can make you feel dizzy, short of breath, and tired.

• Yellowing of the skin, eyes, and mouth (jaundice).  This symptom is common. Sickle cells don’t live as long as normal red blood cells. They die faster than the liver can filter them out. The yellow color is caused by a substance (bilirubin) that is released when the red blood cells die.

• Pain crisis, or sickle crisis. When sickle cells move through small blood vessels, they can get stuck. They can block blood flow and cause pain. The sudden pain can occur anywhere. But it most often happens in the chest, arms, and legs. Blocked blood flow may also cause tissue death.

• Acute chest syndrome. This condition occurs when sickle cells stick together and block oxygen flow in the tiny vessels in the lungs. It can be life-threatening. It often happens suddenly when the body is under stress from infection, fever, or dehydration. Symptoms may seem like pneumonia. They can include fever, pain, and a violent cough.

• Splenic sequestration (pooling). The spleen becomes enlarged and painful when sickle cells get stuck there. Fewer red blood cells are able to move, causing a sudden drop in hemoglobin. It can be deadly if not treated at once.

• Stroke. A stroke is another sudden and severe problem that occurs with this disease. The sickle cells can block the major blood vessels that bring oxygen to the brain. Any interruption in the flow of blood and oxygen to the brain can cause severe brain damage. If you have a stroke from SCD, you are more likely to have a second and third stroke.

• Priapism. The sickle cells block the blood vessels in the penis, causing great pain. If not treated right away, it can cause erectile dysfunction.

The symptoms of SCD may look like other blood disorders or health problems. Always see your healthcare provider for a diagnosis.

How is sickle cell disease diagnosed?

Your healthcare provider will take your health history and give you a physical exam. You may also have blood tests and other tests.

Many states routinely screen newborns for SCD. Treatment can then begin as soon as possible. Early diagnosis and treatment can reduce the risk of problems.

A blood test called hemoglobin electrophoresis may be done. It can tell if you are a carrier of SCD. It can also tell if you have any of the diseases linked with the sickle cell gene.

How is sickle cell disease treated?

Treatment will depend on your symptoms, age, and general health. It will also depend on how severe the condition is.

Early diagnosis and preventing further problems is critical in treating SCD. Treatment goals include preventing organ damage (including strokes), preventing infection, and treating symptoms. Treatment may include:

• Pain medicines. These are used for sickle cell crises.

• Drinking plenty of water daily (8 to 10 glasses). Doing so can prevent and treat pain crises. In some cases, IV (intravenous) fluids may be needed.  

• Blood transfusions. These may help treat anemia and prevent stroke. They are also used to dilute the sickled hemoglobin with normal hemoglobin. It is done to treat chronic pain, acute chest syndrome, splenic sequestration, and other emergencies.

• Red blood cell exchange.This process removes some abnormal red blood cells and replaces them with healthy red blood cells from a donor. This can help improve symptoms.

• Vaccines and antibiotics. These are used to prevent infections.

• Folic acid. This B vitamin helps prevent severe anemia.

• Hydroxyurea. This medicine helps reduce the frequency of pain crises and acute chest syndrome. It may also help decrease the need for blood transfusions.

• Voxelotor. This medicine is approved for people age 4 and older to reduce pain crises and improve anemia caused by red blood cell destruction.

• Crizanlizumab. This medicine is approved for people age 16 and older to reduce pain crises.

• L-glutamine. This medicine is approved for people age 5 and older to reduce pain crises.

• Regular eye exams. These are done to screen for an eye condition called retinopathy.  

• Bone marrow transplant. A transplant can cure some people with SCD. The decision to have a transplant is based on the severity of the disease and finding a suitable donor. These decisions need to be discussed with your provider. Transplants are done only at specialized medical centers.

• Gene therapyNew gene therapies have been approved to treat SCD. Talk with your provider (or your child's provider) about these treatments.

What are possible complications of sickle cell disease?

SCD can affect any major organ. The liver, heart, kidneys, gallbladder, eyes, bones, and joints can all be damaged. They suffer damage from the abnormal function of the sickle cells and their inability to flow through the small blood vessels correctly. Problems may include:

• Increased infections and fever

• Leg ulcers or serious sores

• Bone tissue damage or death

• Early gallstones

• Kidney damage and loss of body water in the urine

• Eye damage

• Multiple organ failure

• Acute chest syndrome causing lung damage. This is a medical emergency.

• Anemia

• Blood clots

• Painful swelling of hands and feet

Living with sickle cell disease

SCD is an ongoing (chronic) condition. You may not be able to fully prevent the complications of this disease but living a healthy lifestyle may reduce some of the problems. This includes doing things such as:

• Eating a healthy diet with lots of fruits, vegetables, whole grains, and protein

• Getting enough sleep

• Drinking lots of fluids

Stay away from things that may trigger a crisis, such as:

• High altitudes

• Cold weather or sudden changes in temperature

• Swimming in cold water

• Heavy physical labor

• Medicines for nasal congestion (decongestants). They cause blood vessels to narrow (constrict).

• Stress or exhaustion

• Alcohol

• Smoking

Prevent infections by:

• Getting vaccines as recommended by your healthcare provider

• Washing your hands often

• Staying away from people who are sick

• Getting regular dental exams

• Following food safety guidelines when cooking, eating, and preparing foods

Key points about sickle cell disease

• Sickle cell disease (SCD) is an inherited blood disorder.

• With SCD, the hemoglobin in red blood cells is abnormal. This damages the red blood cells.

• SCD prevents the hemoglobin in red blood cells from carrying oxygen to all parts of the body.

• Sickle cells clump together, blocking small blood vessels and causing painful and damaging problems.

• SCD is treated with pain medicines as needed, drinking 8 to 10 glasses of water each day, blood transfusions, and medicines.

• Recently approved gene therapies offer new treatment possibilities

Next steps

Tips to help you get the most from a visit to your healthcare provider:

• Know the reason for your visit and what you want to happen.

• Before your visit, write down questions you want answered.

• Bring someone with you to help you ask questions and remember what your provider tells you.

• At the visit, write down the name of a new diagnosis and any new medicines, treatments, or tests. Also write down any new directions your provider gives you.

• Know why a new medicine or treatment is prescribed and how it will help you. Also know what the side effects are.

• Ask if your condition can be treated in other ways.

• Know why a test or procedure is recommended and what the results could mean.

• Know what to expect if you do not take the medicine or have the test or procedure.

• If you have a follow-up appointment, write down the date, time, and purpose for that visit.

• Know how you can contact your healthcare provider if you have questions.