Sickle cell anemia refers to a group of genetic blood disorders that affect a person’s levels of hemoglobin, the protein in red blood cells that transports oxygen. Sickle cell anemia causes a person’s red blood cells to become sickle-shaped rather than disc-shaped, which can result in pain, breathing difficulties, and other complications.
Sickle cell disease is a group of disorders that pass from parents to children in their genes. The most serious form of sickle cell disease is sickle cell anemia. Sickle cell anemia interferes with hemoglobin — the main protein responsible for carrying oxygen in your red blood cells. Sickle cell anemia changes the shape of red blood cells from disc-like and flexible to crescent-shaped, sticky, and stiff.
This difference in shape means red blood cells can block your blood flow in different body parts, causing episodes of severe pain called sickle cell crises. Because incorrectly shaped blood cells don’t carry enough oxygen, sickle cell disease can lead to anemia, or oxygen shortage in the blood. The condition is lifelong, but treatments may help to prolong life and reduce symptoms.
Sickle cell symptoms differ between individuals. Many people have chronic, low-level pain, with or without occasional sickle cell crises, while others have multiple crises each year. The degree of anemia also varies.
Infants with sickle cell anemia generally don't develop symptoms until after they're 6 months old, when their level of fetal hemoglobin declines. Before then, fetal hemoglobin protects red blood cells from sickling.
Sickle crises are the most common complication of sickle cell anemia. The pain of a sickle cell crisis starts suddenly and may last anywhere from hours to weeks. Pain can occur anywhere in the body, but you might be most likely to feel it in the following areas:
Legs
Arms
Chest
Back
Pain may be accompanied by tenderness, swelling, and redness over the area of the blocked blood flow.
In young children, blockages frequently occur in the hands and feet, causing acute, painful swelling known as dactylitis.
Painful crises are the most common reason for emergency room visits and hospital stays for people with sickle cell anemia.
Some people can treat sickle cell crises at home with rest, pain relievers, and hydration, while others require hospitalization and measures like intravenous (IV) fluids, oxygen therapy, and strong pain medication.
Sickle cell anemia causes hemolytic anemia, which occurs when the body destroys sickled red blood cells. A healthy red blood cell lives for around 120 days, while a sickled cell may die in 10 to 20 days. This can lead to a shortage of red blood cells and low oxygen supply to the organs.
These symptoms often resemble other health problems, so seeing a doctor for diagnosis is essential. People with hemolytic anemia due to sickle cell anemia may have blood in their urine.
Emergency symptoms of severe anemia include the following:
Severe weakness
Breathlessness
Extremely rapid heart rate
A physician with special training in blood disorders, known as a hematologist, can identify the best way to manage the anemia associated with sickle cell anemia.
Several types of sickle cell disease may develop, affecting how often people experience sickle cell crises and how severe they may be. The type of anemia depends on which sickle-cell-anemia-linked gene passes between parents and their children, as well as how many copies they may pass on.
The most common types include:
Hemoglobin SS (HbSS) Around 65 percent of people with sickle cell disease have HbSS, a severe type. People with HbSS inherit an abnormal gene connected to hemoglobin production, hemoglobin S, from both parents. This affects almost all hemoglobin and leads to chronic anemia. When doctors use the term “sickle cell anemia,” they are often referring to HbSS.
Hemoglobin SC (HbSC) About 1 in 4 people with sickle cell disease have HbSC, which is mild to moderate. It develops when a person inherits a hemoglobin S gene from only one parent and a hemoglobin C gene, a different faulty type, from the other.
Hemoglobin (HbS) Beta Thalassemia Plus (Beta +) People with HbS beta + have a hemoglobin S gene from one parent and an abnormal gene known as beta thalassemia from the other. People with this type of HbS beta thalassemia generally have mild symptoms, and around 8 in every 100 people living with sickle cell disease have HbS beta +.
Hemoglobin (HbS) beta thalassemia zero (beta 0) This type of hemoglobin beta thalassemia occurs in around 2 of every 100 people with sickle cell disease and causes severe symptoms similar to HbSS. Doctors also use the term “sickle cell anemia” to refer to HbS beta 0.
Other rare types involve different gene changes, including:
A long-lasting, painful erection: If sickled cells build up in your penis, it can cause an ongoing erection that causes pain, also known as priapism. If this lasts for four hours or longer, seek emergency care immediately.
Acute chest syndrome: This life-threatening sickle cell anemia complication occurs when sickled cells block oxygen-rich blood from the lungs. It can injure the lungs, cause breathlessness, and reduce the body’s oxygen supply.
Avascular necrosis: If sickled cells block the blood supply to the bones, the tissue may die, and joints can narrow. This most often affects the hip in people with sickle cell anemia.
Blood clots: Sickled cells have a higher chance of forming blood clots than healthy cells, meaning the clots can lodge in a deep vein or a lung. These can cause severe illness or death.
Chronic pain: People with chronic pain due to sickle cell anemia may feel it for longer than six months.
Eye problems: Altered red blood cells can block blood vessels in the eye, often in the light-detecting layer of cells at the back of the eye known as the retina. This can lead to sudden and severe vision loss, possibly causing blindness.
Gallstones: Bilirubin is a pigment the body produces during the breakdown of red blood cells. The bodies of people with sickle cell anemia break down cells faster, which can lead to a buildup of bilirubin. This can cause gallstones that may block the gallbladder.
Infections: Sickled cells can affect how the spleen works. As this is a key part of the immune system’s defense against infections, sickle cell crises may increase a person’s risk of life-threatening bacterial infections.
Organ failure: Blocked blood and oxygen supply can damage the kidneys, heart, and other organs, sometimes leading to organ failure.
Pulmonary hypertension: High blood pressure in the lungs can lead to breathlessness and fatigue for people with sickle cell anemia, and it can be fatal. This is most common in adults with the condition.
Splenic sequestration: Mostly before 6 years of age, children may experience a potentially life-threatening splenic sequestration crisis in which sickle cells block the narrow blood vessels of the spleen, causing belly pain, an enlarged spleen, pale skin, and a rapid heartbeat.
Stroke: Sickled cells can block blood vessels that feed the brain with oxygen, reducing your brain’s access to oxygen. This can cause a stroke for around 1 in 10 people with sickle cell anemia.
Call 911 or visit the emergency room if you or your child show any sickle cell anemia symptoms, including fever, stroke, and other complications like these.
A fever of 101.5 degrees F (38.5 degrees C), especially in children, who have a higher risk of infection than adults
Paralysis or weakness on one side of the arms, legs, or face
During some crises, drinking plenty of fluids and taking nonsteroidal anti-inflammatory drugs (NSAIDs) may help to manage the pain. But if pain management is not possible, a hospital may be able to provide more effective pain relief.
Sickle cell anemia is the most severe type of sickle cell disease, causing anemia symptoms, pain crises, jaundice, and swelling of the hands and feet.
Some symptoms may resemble those of other types of hemolytic anemia, and the complications can affect many organs, vision, breathing, and sexual function.
If the pain is hard to tolerate or manage and you have concerns about whether symptoms may result from sickle cell anemia, a doctor's visit is the best way to rule out other health problems and seek effective treatment.
