Sickle cell anemia is caused by a
mutation in the gene that tells your body to make the red, iron-rich compound
that gives blood its red color (hemoglobin). Hemoglobin allows red blood cells
to carry oxygen from your lungs to all parts of your body. In sickle cell
anemia, the abnormal hemoglobin causes red blood cells to become rigid, sticky
and misshapen.
The sickle cell gene is passed from
generation to generation in a pattern of inheritance called autosomal recessive
inheritance. This means that both the mother and the father must pass on the
defective form of the gene for a child to be affected.
If only one parent passes the sickle
cell gene to the child, that child will have the sickle cell trait. With one
normal hemoglobin gene and one defective form of the gene, people with the
sickle cell trait make both normal hemoglobin and sickle cell hemoglobin. Their
blood might contain some sickle cells, but they generally don't have symptoms.
But they are carriers of the disease, which means they can pass the gene to
their children.
Risk
factors
For a baby to be born with sickle
cell anemia, both parents must carry a sickle cell gene. In the United States,
it most commonly affects black people.
Complications
Sickle cell anemia can lead to a
host of complications, including:
- Stroke.
A stroke can occur if sickle cells block blood flow to an area of your
brain. Signs of stroke include seizures, weakness or numbness of your arms
and legs, sudden speech difficulties, and loss of consciousness. If your
baby or child has any of these signs and symptoms, seek medical treatment
immediately. A stroke can be fatal.
- Acute chest syndrome.
This life-threatening complication causes chest pain, fever and difficulty
breathing. Acute chest syndrome can be caused by a lung infection or by
sickle cells blocking blood vessels in your lungs. It might require
emergency medical treatment with antibiotics and other treatments.
- Pulmonary hypertension. People with sickle cell anemia can develop high blood
pressure in their lungs (pulmonary hypertension). This complication
usually affects adults rather than children. Shortness of breath and
fatigue are common symptoms of this condition, which can be fatal.
- Organ damage.
Sickle cells that block blood flow through blood vessels immediately
deprive the affected organ of blood and oxygen. In sickle cell anemia,
blood is also chronically low on oxygen. Chronic deprivation of
oxygen-rich blood can damage nerves and organs in your body, including
your kidneys, liver and spleen. Organ damage can be fatal.
- Blindness.
Sickle cells can block tiny blood vessels that supply your eyes. Over
time, this can damage the portion of the eye that processes visual images
(retina) and lead to blindness.
- Leg ulcers.
Sickle cell anemia can cause open sores, called ulcers, on your legs.
- Gallstones.
The breakdown of red blood cells produces a substance called bilirubin. A
high level of bilirubin in your body can lead to gallstones.
- Priapism.
Men with sickle cell anemia can have painful, long-lasting erections, a
condition called priapism. As occurs in other parts of the body, sickle
cells can block the blood vessels in the penis. This can damage the penis
and lead to impotence.
DIAGNOSIS
A blood test can check for hemoglobin S — the defective form of hemoglobin
that underlies sickle cell anemia. In the United States, this blood test is
part of routine newborn screening done at the hospital. But older children and
adults can be tested, too.
In adults, a blood sample is drawn from a vein in the arm. In young children
and babies, the blood sample is usually collected from a finger or heel. The
sample is then sent to a laboratory, where it's screened for hemoglobin S.
If the screening test is negative, there is no sickle cell gene present. If
the screening test is positive, further tests will be done to determine whether
one or two sickle cell genes are present.
Additional tests
If you or your child has sickle cell anemia, a blood test to check for a low
red blood cell count (anemia) will be done. Your doctor might suggest
additional tests to check for possible complications of the disease.
If you or your child carries the sickle cell gene, you'll likely be referred
to a genetic counselor.
Tests to detect sickle cell genes before birth
Sickle cell disease can be diagnosed in an unborn baby by sampling some of
the fluid surrounding the baby in the mother's womb (amniotic fluid) to look
for the sickle cell gene. If you or your partner has been diagnosed with sickle
cell anemia or sickle cell trait, ask your doctor about whether you should
consider this screening. Ask for a referral to a genetic counselor who can help
you understand the risk to your baby.
TREATMENT
Bone marrow transplant, also known
as stem cell transplant, offers the only potential cure for sickle cell anemia.
It's usually reserved for people younger than age 16 because the risks increase
for people older than 16. Finding a donor is difficult, and the procedure has
serious risks associated with it, including death.
As a result, treatment for sickle
cell anemia is usually aimed at avoiding crises, relieving symptoms and
preventing complications. Babies and children age 2 and younger with sickle
cell anemia should make frequent visits to a doctor. Children older than 2 and
adults with sickle cell anemia should see a doctor at least once a year,
according to the Centers for Disease Control and Prevention.
Treatments might include medications
to reduce pain and prevent complications, and blood transfusions, as well as a
bone marrow transplant.
Medications
Medications used to treat sickle
cell anemia include:
- Antibiotics.
Children with sickle cell anemia may begin taking the antibiotic
penicillin when they're about 2 months old and continue taking it until
they're at least 5 years old. Doing so helps prevent infections, such as
pneumonia, which can be life-threatening to an infant or child with sickle
cell anemia.
As an
adult, if you've had your spleen removed or had pneumonia, you might need to
take penicillin throughout your life.
- Pain-relieving medications. To relieve pain during a sickle cell crisis, your
doctor might prescribe pain medications.
- Hydroxyurea (Droxia, Hydrea). When taken daily, hydroxyurea reduces the frequency of
painful crises and might reduce the need for blood transfusions and
hospitalizations. Hydroxyurea seems to work by stimulating production of
fetal hemoglobin — a type of hemoglobin found in newborns that helps
prevent the formation of sickle cells.
Hydroxyurea
increases your risk of infections, and there is some concern that long-term use
of this drug might cause problems later in life for people who take it for many
years. More study is needed.
Your
doctor can help you determine if this drug might be beneficial for you or your
child. Don't take the drug if you're pregnant.
Assessing
stroke risk
Using a special ultrasound machine
(transcranial), doctors can learn which children have a higher risk of stroke.
This painless test, which uses sound waves to measure blood flow, can be used
on children as young as 2 years. Regular blood transfusions can decrease stroke
risk.
Vaccinations
to prevent infections
Childhood vaccinations are important
for preventing disease in all children. They're even more important for
children with sickle cell anemia because their infections can be severe.
Your doctor will make sure your
child receives all of the recommended childhood vaccinations. Vaccinations,
such as the pneumococcal vaccine and the annual flu shot, are also important
for adults with sickle cell anemia.
Blood
transfusions
In a red blood cell transfusion, red
blood cells are removed from a supply of donated blood, then given
intravenously to a person with sickle cell anemia.
Blood transfusions increase the
number of normal red blood cells in circulation, helping to relieve anemia. In
children with sickle cell anemia at high risk of stroke, regular blood
transfusions can decrease the risk. Transfusions can also be used to treat
other complications of sickle cell anemia, or they can be given to prevent
complications.
Blood transfusions carry some risk,
including infection and excess iron buildup in your body. Because excess iron
can damage your heart, liver and other organs, people who undergo regular
transfusions might need treatment to reduce iron levels.
Bone
marrow transplant
A bone marrow transplant, also
called a stem cell transplant, involves replacing bone marrow affected by
sickle cell anemia with healthy bone marrow from a donor. The procedure usually
uses a matched donor, such as a sibling, who doesn't have sickle cell anemia.
For many, donors aren't available. But stem cells from umbilical cord blood
might be an option.
Because of the risks associated with
a bone marrow transplant, the procedure is recommended only for people, usually
children, who have significant symptoms and problems from sickle cell anemia.
If a donor is found, the person with
sickle cell anemia receives radiation or chemotherapy to destroy or reduce his
or her bone marrow stem cells. Healthy stem cells from the donor are injected
intravenously into the bloodstream of the person with sickle cell anemia, where
they migrate to the bone marrow and begin generating new blood cells.
The procedure requires a lengthy
hospital stay. After the transplant, you'll receive drugs to help prevent
rejection of the donated stem cells. Even so, your body might reject the transplant,
leading to life-threatening complications.
Treating
sickle cell complications
Doctors treat most complications of
sickle cell anemia as they occur. Treatment might include antibiotics,
vitamins, blood transfusions, pain-relieving medicines, other medications and
possibly surgery, such as to correct vision problems or to remove a damaged
spleen.
Experimental
treatments
Scientists are studying new
treatments for sickle cell anemia, including:
- Gene therapy.
Researchers are exploring whether inserting a normal gene into the bone
marrow of people with sickle cell anemia will result in normal hemoglobin.
Scientists are also exploring the possibility of turning off the defective
gene while reactivating another gene responsible for the production of fetal
hemoglobin — a type of hemoglobin found in newborns that prevents sickle
cells from forming.
Potential
treatments using gene therapy are a long way off, however.
- Nitric oxide.
People with sickle cell anemia have low levels of nitric oxide in their
blood. Nitric oxide is a gas that helps keep blood vessels open and
reduces the stickiness of red blood cells. Treatment with inhaled nitric
oxide might prevent sickle cells from clumping together. Studies on nitric
oxide have shown little benefit so far.
- Drugs to boost fetal hemoglobin production. Researchers are studying various drugs to devise a way
to boost the production of fetal hemoglobin. This is a type of hemoglobin
that stops sickle cells from forming.
Self-management
Lifestyle and home remedies
Taking the following steps to stay healthy may help you avoid complications
of sickle cell anemia:
- Take folic acid supplements daily, and
choose a healthy diet. Bone marrow needs folic acid and
other vitamins to make new red blood cells. Your doctor might recommend a
folic acid supplement. Choose a diet that focuses on a variety of colorful
fruits and vegetables, as well as whole grains.
- Drink plenty of water.
Dehydration can increase your risk of a sickle cell crisis. Drink water
throughout your day, aiming for about eight glasses a day. Increase the
amount of water you drink if you exercise or spend time in a hot, dry
climate.
- Avoid temperature extremes.
Exposure to extreme heat or cold can increase your risk of a sickle cell
crisis.
- Exercise regularly, but don't overdo it.
Talk with your doctor about how much exercise is right for you.
- Use over-the-counter (OTC) medications
with caution. Use OTC pain medications, such as ibuprofen
(Advil, Motrin IB, Children's Motrin, others) or naproxen sodium (Aleve)
sparingly, if at all, because of the possible effect on your kidneys. Ask
your doctor before taking OTC drugs.
Coping and support
If you or someone in your family has sickle cell anemia, you may want help
with the stresses of this lifelong disease. Consider:
- Finding someone to talk with.
Sickle cell centers and clinics can provide information and counseling.
Ask your doctor or the staff at a sickle cell center if there are support
groups for families in your area. Talking with others who are facing the
same challenges you are can be helpful.
- Exploring ways to cope with the pain.
Work with your doctor to find ways to control your pain. Pain medications
can't always take all the pain away. Different techniques work for
different people, but it might be worth trying heating pads, hot baths,
massages or physical therapy.
- Learning about sickle cell anemia to make
informed decisions about care. If you have a child with
sickle cell anemia, learn as much as you can about the disease. Ask
questions during your child's appointments. Ask your health care team to
recommend good sources of information.
Prevention
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. He or she can also explain possible treatments, preventive
measures and reproductive options.
