Sickle Cell Disease: Causes, Symptoms, Diagnosis and Treatment

Sickle cell disease (SCD) is a group of inherited red blood cell disorders. It affects hemoglobin, the protein in red blood cells that carries oxygen around the body.

What happens in the blood

In SCD, hemoglobin forms stiff rods inside red blood cells, bending the normally disc-shaped cells into rigid crescent, or sickle, shapes. The sickle cells can't flex, and many burst as they travel through blood vessels.

• Anemia. Sickle cells usually last only 10 to 20 days instead of the normal 90 to 120, and the body may not make new ones fast enough. The result is too few red blood cells — anemia — which can cause fatigue.
• Pain crises. Sickle cells can stick to vessel walls and slow or block blood flow, starving nearby tissue of oxygen. That can trigger sudden, severe attacks of pain, called pain crises, which can strike without warning and may need hospital treatment.

Causes

SCD is caused by a variant (change) in a gene that tells the body how to make part of hemoglobin — sometimes called a sickle cell gene.

• People with SCD inherit two sickle cell genes, one from each parent.
• People with one have sickle cell trait. They are generally healthy but can pass the gene to their children.

Who is affected

In the United States, most people with SCD are African American:

• about 1 in 13 Black or African American babies is born with sickle cell trait;
• about 1 in 365 is born with sickle cell disease.

SCD also affects some people of Hispanic, southern European, Middle Eastern or Asian Indian descent.

Symptoms

Signs usually appear in the first year of life, typically around 5 or 6 months. Early symptoms may include:

• painful swelling of the hands and feet;
• fatigue or fussiness from anemia;
• yellowing of the skin (jaundice) or the whites of the eyes (icterus).

Effects vary from person to person and over time. Most signs come from complications: severe pain, anemia, organ damage and infections.

Diagnosis

• A blood test shows whether someone has SCD or sickle cell trait, and genetic tests can show whether they carry one or two copies of the gene, confirming unclear results.
• Every state screens newborns for SCD, among many other treatable conditions, so treatment can start early.
• SCD can also be diagnosed before birth using a sample of amniotic fluid or placental tissue, and people planning to have children can be tested to learn how likely their children are to have SCD.

Treatment

A medical team, usually including a hematologist (a blood disease specialist), works out a treatment plan. Options include:

• Hydroxyurea, a medicine that reduces sickling and can help prevent serious symptoms. It can be used by adults and children as young as 9 months, but is not safe in pregnancy.
• Pain relievers for sudden or long-lasting pain.
• Antibiotics to help prevent infections in young children.
• Blood transfusions for severe anemia, or to prevent further complications after serious ones such as a stroke.
• Treatment of specific complications, such as blood pressure medicines or vitamins for deficiencies.
• Bone marrow or stem cell transplantation, which can cure SCD. Because it is risky, it is usually reserved for children with severe disease, and it needs a closely matched donor — usually a brother or sister.
• Gene therapies for people 12 and older who have had repeated crises. Some of the patient's own blood stem cells are given new DNA or have their DNA edited, then returned to the body, where they make healthy hemoglobin — reducing complications, including crises.

Complementary approaches may ease pain, especially when medicine isn't enough: cognitive behavioral therapy, acupuncture, exercise and movement such as yoga, massage, meditation and mindfulness, and virtual reality.

To stay as healthy as possible, get regular medical care and routine vaccinations, live a healthy lifestyle, and avoid situations that can set off a pain crisis.

Sources

Based on "Sickle Cell Disease," MedlinePlus, U.S. National Library of Medicine, drawing on the National Heart, Lung, and Blood Institute (NIH); a work of the United States government in the public domain.