Sickle cell anemia, or sickle cell disease (SCD), is a genetic disease of the red blood cells (RBCs). Normally RBCs are shaped like discs, which gives them the flexibility to travel through even the smallest blood vessels. However, with this disease, the RBCs have an abnormal crescent (“sickle”) shape. This makes them sticky and rigid. They can get trapped in small vessels and block blood from reaching different parts of the body. This can cause pain and tissue damage.
SCD is an autosomal recessive condition. You need two copies of the gene to have the disease. If you have only one copy of the gene, you are said to have sickle cell trait.
Symptoms of sickle cell anemia usually show up at a young age. They may appear in babies as early as 4 months old, but generally occur around the 6-month mark.
While there are multiple types of SCD, they all have similar symptoms at different levels of severity. These include:
- excessive fatigue or irritability (from anemia)
- fussiness (in babies)
- bedwetting (from associated kidney problems)
- jaundice (yellowing of the eyes and skin)
- swelling and pain in hands and feet
- frequent infections
- chest pain
Hemoglobin is the protein in RBCs that carries oxygen. It normally has two alpha chains and two beta chains. The four main types of sickle cell anemia are caused by different mutations in these genes.
Hemoglobin SS Disease
Hemoglobin SS disease is the most common type of sickle cell disease. It occurs when you inherit copies of the hemoglobin S gene from both parents. This forms hemoglobin known as Hb SS. As the most severe form of SCD, individuals with this form also experience the worst symptoms at a higher rate.
Hemoglobin SC Disease
Hemoglobin SC disease is the second most common type of sickle cell disease. It occurs when you inherit the Hb C gene from one parent and the Hb S gene from the other. Individuals with Hb SC have similar symptoms to individuals with Hb SS. However, the anemia is less severe.
Hemoglobin SB+ (Beta) Thalassemia
Hemoglobin SB+ (beta) thalassemia affects beta globin gene production. The size of the red blood cell is reduced because less beta protein is made. If inherited with the Hb S gene, you will have Hemoglobin S Beta thalassemia. Symptoms are not as severe.
Beta-zero thalassemia is the second type of beta thalassemia. It has similar symptoms to Hb SS anemia. However, sometimes the symptoms of beta-zero thalassemia are more severe. It is associated with a poorer prognosis.
People who only inherit a mutated gene from only one parent are said to have sickle cell trait. They may have no symptoms or reduced symptoms.
Children are only at risk for sickle cell if both parents carry sickle cell trait. A blood test
called a hemoglobin electrophoresis can also determine which type you might carry.
People from regions that have endemic malaria are more likely to be carriers. This includes people from:
- the Mediterranean
- Saudi Arabia
SCD can cause severe complications. These complications appear when the sickle cells block vessels in different areas of the body. Painful or damaging blockages are called sickle cell crises.
Anemia is a shortage of RBCs. Sickle cells are easily broken. This breaking apart of RBCs is called chronic hemolysis. RBCs generally live for about 120 days. Sickle cells live for a maximum of 10 to 20 days.
Hand-Foot Syndrome occurs when sickle-shaped RBCs block blood vessels in the hands or feet. This causes the hands and feet to swell. It can also cause leg ulcers. Swollen hands and feet are often the first sign of sickle cell anemia in babies.
Splenic sequestration is a blockage of the splenic vessels by sickle cells. It causes a sudden, painful enlargement of the spleen.
Delayed growth often occurs in people with SCD. Children are generally shorter but regain their height by adulthood. Sexual maturation may also be delayed. This happens because sickle cell RBCs can’t supply enough oxygen and nutrients.
Neurological complications include seizures, bleeding in the brain, or even coma. They are caused by brain blockages. Immediate treatment should be sought.
Blindness is caused by blockages in the vessels supplying the eyes. This can damage the retina.
Skin ulcers in the legs can occur if small vessels there are blocked.
Heart Disease and Chest Syndrome
Since SCD interferes with blood oxygen supply, it affects the blood vessels. Over time, this can lead to an enlarged heart and subsequent heart disease. This can also lead to pain known as chest syndrome. High blood pressure (hypertension) and stroke may also develop.
Priapism is a lingering, painful erection that can be seen in some men with sickle cell. This happens when the blood vessels in the penis are blocked. It can lead to impotence if left untreated.
Gallstones are one complication not caused by a vessel blockage. Instead, they are caused by the breakdown of RBCs. A byproduct of this breakdown is bilirubin. High levels of bilirubin can lead to gallstones. These are also called pigment stones.
All newborns in the United States are screened for sickle cell disease. Prebirth testing looks for the sickle cell gene in your amniotic fluid.
In children and adults, one or more of the following procedures may also be used to diagnose sickle cell.
Detailed Patient History
This condition often first appears as acute pain in the hands and feet. Patients may also have:
- severe pain in the bones
- painful enlargement of the spleen
- growth problems
- respiratory infections
- ulcers of the legs
- heart problems
Your doctor may want to test you for sickle cell anemia if you have any of the symptoms mentioned above.
Several blood tests can be used to look for SCD:
- blood counts can reveal an abnormal Hb level in the range of 6 to 8 g/dL
- blood films may show RBCs that appear as irregularly contracted cells
- sickle solubility tests look for the presence of Hb S
Hb electrophoresis is always needed to confirm the diagnosis of sickle cell. It measures the different types of hemoglobin in the blood.
A number of different treatments are available for SCD:
- Antibiotics like penicillin may be given from 2 months of age to 5 years. They help prevent pneumonia in sickle cell patients.
- Supplemental oxygen is given through a mask. It makes breathing easier and improves oxygen levels in the blood.
- Pain medication is used to relieve the pain during a sickle crisis. You may need over-the-counter drugs or strong prescription pain medication like morphine.
- Hydroxyurea (Droxia, Hydrea) helps to increase production of fetal hemoglobin. It may reduce the number of blood transfusions.
- Immunizations can help prevent infections. Patients tend to have lower immunity.
- Surgery may be used to treat persistent and painful erections.
Bone marrow transplant has been used to treat sickle cell anemia. Children younger than 16 years of age who have severe complications and have a matching donor are the best candidates.
Blood transfusions can also treat sickle cell anemia. Packed red cells are removed from donated blood and given to patients. This improves transport of oxygen and nutrients.
There are things you can do at home to help your sickle cell symptoms:
- Use heating pads for pain relief.
- Take folic acid supplements, as recommended by your doctor.
- Adequate fruits, vegetables, and whole-wheat grains are important and can help your body make more RBCs.
- Drink more water to reduce the chances of sickle cell crises.
- Exercise regularly and reduce stress to reduce crises, too.
Support groups can also help you deal with this condition.
The prognosis of the disease varies. Some patients have frequent and painful sickle cell crises. Others only rarely have attacks.
Sickle cell anemia is an inherited disease. Talk to a genetic counselor if you are worried that you might be a carrier. This can help you understand possible treatments, preventive measures, and reproductive options.