Sickle Cell Anemia

    Definition

    Sickle cell anemia (uh-NEE-me-uh) is the most common form of sickle cell disease (SCD). SCD is a serious disorder in which the body makes sickle-shaped red blood cells. “Sickle-shaped” means that the red blood cells are shaped like a crescent. Sickle cells are stiff and sticky. They tend to block blood flow in the blood vessels of the limbs and organs. Blocked blood flow can cause pain, serious infections, and organ damage.

    Sickle cell occurs in about 1 in every 500 African-American births. About 2 million Americans, or 1 in 12 African Americans, carry the sickle cell trait.

    Alternative Names

    Hemoglobin SS disease (Hb SS); Sickle Cell Disease

    Causes

    Sickle cell anemia is an inherited disease. People who have the disease inherit two genes for sickle hemoglobin—one from each parent.
    Sickle hemoglobin causes red blood cells to develop a sickle, or crescent, shape. Sickle cells are stiff and sticky. They tend to block blood flow in the blood vessels of the limbs and organs. Blocked blood flow can cause pain, serious infections, and organ damage.

    Sickle Cell Trait

    • People who inherit a sickle hemoglobin gene from one parent and a normal gene from the other parent have a condition called sickle cell trait. Their bodies make sickle hemoglobin and normal hemoglobin.
    • People who have sickle cell trait usually have few, if any, symptoms and lead normal lives. However, some people may have medical complications.
    • People who have sickle cell trait can pass the sickle hemoglobin gene to their children. The following image shows an example of an inheritance pattern for sickle cell trait.

    Symptoms

    The signs and symptoms of sickle cell anemia vary. Some people have mild symptoms. Others have very severe symptoms and often are hospitalized for treatment. Sickle cell anemia is present at birth, but many infants don’t show any signs until after 4 months of age.

    The most common signs and symptoms are linked to anemia and pain. Other signs and symptoms are linked to the disease’s complications.

    Signs and Symptoms Related to Anemia

    The most common symptom of anemia is fatigue (feeling tired or weak). Other signs and symptoms of anemia may include:

    •    Shortness of breath
    •    Dizziness
    •    Headaches
    •    Coldness in the hands and feet
    •    Paler than normal skin or mucous membranes (the tissue that lines your nose, mouth, and other organs and body cavities)
    •    Jaundice (a yellowish color of the skin or whites of the eyes)

    Signs and Symptoms Related to Pain

    Sudden pain throughout the body is a common symptom of sickle cell anemia. This pain is called a sickle cell crisis. Sickle cell crises often affect the bones, lungs, abdomen, and joints.These crises occur when sickled red blood cells block blood flow to the limbs and organs. This can cause pain and organ damage.

    The pain from sickle cell anemia can be acute or chronic, but acute pain is more common. Acute pain is sudden and can range from mild to very severe. The pain usually lasts from hours to as long as a week or more. Many people who have sickle cell anemia also have chronic pain, especially in their bones. Chronic pain often lasts for weeks or months and can be hard to bear and mentally draining. Chronic pain may limit your daily activities.

    Almost all people who have sickle cell anemia have painful crises at some point in their lives. Some have these crises less than once a year. Others may have crises once a month or more. Repeated crises can damage the bones, kidneys, lungs, eyes, heart, and liver. This type of damage happens more often in adults than in children.

    Many factors can play a role in sickle cell crises. Often, more than one factor is involved and the exact cause isn’t known. You can control some factors. For example, the risk of a sickle cell crisis increases if you’re dehydrated (your body doesn’t have enough fluids). Drinking plenty of fluids can lower the risk of a painful crisis.

    You can’t control other factors, such as infections. Painful crises are the leading cause of emergency room visits and hospital stays for people who have sickle cell anemia.

    Exams and Tests

    A simple blood test, done at any time during a person’s lifespan, can detect whether he or she has sickle hemoglobin. However, early diagnosis is very important.

    In the United States, all States mandate testing for sickle cell anemia as part of their newborn screening programs. The test uses blood from the same blood samples used for other routine newborn screening tests. The test can show whether a newborn infant has sickle hemoglobin.

    Test results are sent to the doctor who ordered the test and to the baby’s primary care doctor. It’s important to give the correct contact information to the hospital. This allows the baby’s doctor to get the test results as quickly as possible.

    Health providers from a newborn screening followup program may contact you directly to make sure you’re aware of the test results.
    If the test shows some sickle hemoglobin, a second blood test is done to confirm the diagnosis. The second test should be done as soon as possible and within the first few months of life.

    The primary care doctor may send you to a hematologist for a second blood test. A hematologist is a doctor who specializes in blood diseases and disorders. This doctor also can provide treatment for sickle cell disease if needed.

    Doctors also can diagnose sickle cell disease before birth. This is done using a sample of amniotic fluid or tissue taken from the placenta. (Amniotic fluid is the fluid in the sac surrounding a growing embryo. The placenta is the organ that attaches the umbilical cord to the mother’s womb.)

    Testing before birth can be done as early as 10 weeks into the pregnancy. This testing looks for the sickle hemoglobin gene, rather than the abnormal hemoglobin that the gene makes.

    Treatments

    Sickle cell anemia has no widely available cure. However, treatments can help relieve symptoms and treat complications. The goals of treating sickle cell anemia are to relieve pain; prevent infections, organ damage, and strokes; and control complications (if they occur).
    Blood and marrow stem cell transplants may offer a cure for a small number of people who have sickle cell anemia. Researchers continue to look for new treatments for the disease.

    Infants who have been diagnosed with sickle cell anemia through newborn screening are treated with antibiotics to prevent infections. Their parents are educated about the disease and how to manage it. These initial treatment steps have greatly improved the outcome for children who have sickle cell anemia.

    Treatment for a sickle cell crisis includes:
    •    Blood transfusions (may also be given regularly to prevent stroke)
    •    Pain medicines
    •    Plenty of fluids

    Other treatments for sickle cell anemia may include:
    •    Hydroxyurea (Hydrea), a medicine that may help reduce the number of pain episodes (including chest pain and difficulty breathing) in some people
    •    Antibiotics to prevent bacterial infections, which are common in children with sickle cell disease

    Treatments for complications of sickle cell anemia may include:
    •    Kidney dialysis or kidney transplant for kidney disease
    •    Drug rehabilitation and counseling for psychological complications
    •    Gallbladder removal in those with gallstone disease
    •    Hip replacement for avascular necrosis of the hip
    •    Treatments, including surgery, for persistent, painful erections (priapism)
    •    Surgery for eye problems
    •    Wound care, zinc oxide, or surgery for leg ulcers

    Possible Complications

    Sickle cell crises can affect many parts of the body and cause many complications.
    •    Acute chest syndrome
    •    Anemia
    •    Blindness/vision impairment
    •    Brain and nervous system (neurologic) symptoms and stroke
    •    Death
    •    Disease of many body systems (kidney, liver, lung)
    •    Drug (narcotic) abuse
    •    Erectile dysfunction (as a result of priapism)
    •    Gallstones
    •    Hemolytic crisis
    •    Infection, including pneumonia, gallbladder inflammation (cholecystitis), bone infection (osteomyelitis), and urinary tract infection
    •    Joint destruction
    •    Leg sores (ulcers)
    •    Loss of function in the spleen
    •    Parvovirus B19 infection, leading to low red blood cell production (aplastic crisis)
    •    Splenic sequestration syndrome
    •    Tissue death in the kidney

    When to Contact a Medical Professional

    Call your health care provider if you have:
    •    Painful crises
    •    Any symptoms of infection (fever, body aches, headache, fatigue)

    Preventions

    Sickle cell anemia is an inherited disease. If a person is born with it, steps should be taken to reduce its complications.

    People who are at high risk of having a child with sickle cell anemia and are planning to have children may want to consider genetic counseling. A counselor can explain the risk (likelihood) of having a child who has the disease. He or she also can help explain the choices that are available.

    You can find information about genetic counseling from health departments, neighborhood health centers, medical centers, and clinics that care for people who have sickle cell anemia.

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