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Sickle Cell Disease

Reviewed by: Robin E. Miller, MD

What Is Sickle Cell Disease?

Sickle cell disease is a blood disorder that's inherited — meaning it's passed down from parents to their children. Babies are born with sickle cell disease when they inherit two abnormal genes (one from each parent). These genes cause the body's red blood cells to change shape.

Normal red blood cells are shaped like discs or donuts with the centers partly scooped out. They are soft and flexible so they can easily move through very small blood vessels and deliver oxygen throughout a person's body.

Sickle cells are stiffer. Instead of being disc shaped, they're curved like crescent moons, or an old farm tool known as a sickle. That's where the disease gets its name.

Sickle cell disease affects a protein in red blood cells called hemoglobin (pronounced: HEE-muh-glow-bin). Hemoglobin helps to carry oxygen throughout the body. Red blood cells with normal hemoglobin move easily through the bloodstream because of their rounded shape and greater flexibility. Normal hemoglobin is called hemoglobin A (HbA for short).

People with sickle cell disease have a kind of hemoglobin called hemoglobin S, or HbS. HbS molecules tend to clump together. This makes red blood cells sticky, stiff, and more fragile. HbS also causes cells to form into a curved, sickle shape.

Red blood cells containing HbS can go back and forth between being shaped normally and being sickle shaped until they eventually become sickle shaped permanently.

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What Happens in the Blood?

Instead of moving through the bloodstream easily, sickle cells can clog blood vessels. When blood can't get where it's needed, the body's tissues and organs don't have the oxygen they need to stay healthy.

Normal red blood cells last about 4 months in the bloodstream. But fragile sickle cells break down after only about 10 to 20 days. This usually causes . Anemia is what happens when the body's number of red blood cells (or amount of hemoglobin) falls below normal. People who are anemic often feel weak, tire more easily, and may appear "run down."

People with sickle cell disease might have other problems because their blood isn't moving through the body as well as it should. For example:

  • a higher chance of getting infections
  • a higher chance of having a stroke
  • a condition called acute chest syndrome, which is caused by inflammation, infection, or blood vessels in the lungs that are blocked by sickled cells.

How Do People Get It?

Sickle cell disease is not , so you can't catch it from someone else or pass it to another person like a cold or an infection.

People with sickle cell disease have it because they inherited two sickle cell genes, one from each parent.

A person who inherits the sickle cell gene from only one parent will not develop the disease, but will have something called  . People with sickle cell trait often don't have any signs of the disease, but they can pass the sickle cell gene on to their own children.

People with sickle cell trait may never know that they carry the gene. That's why doctors recommended that anyone who's not sure if they carry the sickle cell gene get tested to find out for sure. Doctors use a special blood test called a hemoglobin electrophoresis (pronounced: eh-lek-tro-fuh-REE-sis) to look for sickle hemoglobin in a person's blood.

The National Institutes of Health (NIH) recommends that all newborns be screened for sickle cell disease. Testing at birth is now required in every U.S. state. This helps infants with sickle cell disease get the care and treatment they need right away.

What Signs and Problems Can People Have?

Most teens with sickle cell disease have some degree of anemia or a lower amount of hemoglobin in their blood than people who do not have the disease. They may get tired more easily, look pale, or have a fast pulse.

People with sickle cell anemia may develop jaundice (pronounced: JON-dis). This happens because more fragile sickle-shaped red blood cells break down faster. Jaundice can cause a person's skin and whites of the eyes to develop a yellowish tint.

It's also common for people with sickle cell disease to have trouble fighting infections.

Teens with sickle cell disease may grow more slowly and reach puberty later than other people.

People with sickle cell anemia might have times where they feel severe pain in their chest, stomach, arms, legs, or other parts of the body. This happens because sickle cells block blood flow through the small blood vessels in those areas.

Periods of pain are commonly referred to as pain crises. How severe these crises are, how long they last, and how often they happen depends on the person. Some people may have one sickle cell pain crisis a year. Others will have crises more often. Pain crises can be brief or last hours, days, or even weeks. Sometimes pain can be severe enough to require treatment in the hospital.

When people with sickle cell disease get acute chest syndrome, they may have severe chest and abdominal pain, fever, cough, and trouble breathing.

When sickle-shaped cells block blood vessels in the brain, it puts people at risk of having a stroke. Signs of a stroke include headache, seizures, weakness of the arms and legs, speech problems, a droop on one side of the face, and loss of consciousness.

Other possible problems that sickle-shaped cells can cause include , bone or joint damage, gallstones, kidney damage, painful long-lasting erections in males (called priapism), eye damage, and delayed growth.

It is possible for some people to be ill enough to die from the disease, though that doesn't usually happen to young people.

What Will Doctors Do?

Doctors might prescribe a few different kinds of treatments to help with the problems sickle cell disease can cause:

  • Folic acid is a vitamin that helps the body produce new red blood cells.
  • Pain medicines can help relieve the pain of sickle cell crises.
  • Penicillin or other antibiotics can help prevent infections, though doctors usually stop giving penicillin to kids who have sickle cell disease after the age of 5. 
  • Water and drinking lots of fluids can help prevent pain crises; so can avoiding extreme cold or heat.

Some sickle cell crises can be managed at home with pain medicines, rest, and extra fluids. But if a crisis is very intense, a teen may need to go to the hospital for intravenous (IV) fluids and stronger pain medicines.

People with sickle cell anemia occasionally need to get transfusions of healthy red blood cells to help carry oxygen to the tissues of their bodies more effectively and treat complications. A few may need transfusions regularly.

The drug hydroxyurea, when taken every day, helps reduce painful crises and episodes of acute chest syndrome for people with sickle cell disease.

Right now, the only cure for sickle cell disease is stem cell transplant, but it's a complex and risky procedure. Scientists are studying gene therapy as a treatment for sickle cell anemia. One day, it's hoped that doctors can stop the disease by changing or replacing the abnormal gene that causes it.

What Can You Do to Stay Well?

People with sickle cell disease can do most of the stuff everyone else does if they take the right steps. To stay as healthy as possible:

  • Eat a balanced, healthy diet.
  • Take medicines, including folic acid supplements, exactly as your doctor tells you.
  • Drink plenty of fluids to prevent dehydration.
  • Avoid extreme cold or heat.
  • Exercise regularly, but in moderation. Exercise is important for staying healthy, but overdoing it can trigger a crisis in some people, particularly if they become dehydrated, overheated, or exhausted.
  • Get plenty of rest.
  • Avoid alcohol, drugs, and smoking, which can make sickle cell disease and its symptoms worse. Some people with sickle cell disease are prone to lung problems, so smoking is particularly risky.
  • Avoid places where there isn't a lot of oxygen. (For example, it's not a good idea to go hiking at high altitudes or spend lots of time swimming underwater.)
  • Prevent serious infections by contacting your doctor as soon as illness symptoms start. Be sure to get any immunizations (such as pneumonia and flu vaccines) that the doctor recommends, and always call your doctor if you have a high fever (over 101°F/38°C).
  • Learn as much as you can about the disease and see your doctor regularly to help prevent complications.

People with sickle cell disease may need to put some limits on their lives. But with the help of doctors, friends, and family, they can manage the condition and live their lives to the fullest.

Reviewed by: Robin E. Miller, MD
Date reviewed: October 2015