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Overview

What Is Sickle Cell Anemia?

Sickle cell anemia is an inherited form of sickle cell disease. A changed form of hemoglobin makes red blood cells become rigid and crescent- or sickle-shaped instead of flexible and round. These cells can break down too quickly, causing anemia, and can block small blood vessels, reducing blood flow and oxygen delivery. This explains what is sickle cell disease in simple terms: an inherited blood disorder that can affect people who receive disease-causing hemoglobin variants from their biological parents.

Symptoms

Sickle Cell Anemia Symptoms

  • Episodes of severe pain (vaso-occlusive crisis) can occur when sickle-shaped cells block blood flow.
  • Tiredness or weakness can result from anemia.
  • Yellowing of the skin or eyes (jaundice) can occur when red blood cells break down.
  • Swelling of the hands and feet can occur, especially in young children.
  • Frequent infections may occur because sickle cell disease can affect the spleen and immune protection.
  • Pale skin or the pale appearance of the inside of the eyelids may indicate anemia.
  • Delayed growth or puberty can occur in some children and teenagers.
  • Vision changes can develop when blocked blood flow affects the eyes.

SICKLE CELL CRISIS

Sudden severe pain needs attention

Sickle cell symptoms vary by age, disease form, and individual health. A sickle cell crisis may cause sudden, severe pain and may require urgent medical assessment, especially when the pain is unusual, worsening, or not controlled by the person’s care plan.

Causes

Causes of Sickle Cell Anemia

Mutations in the HBB gene can produce hemoglobin S, an abnormal hemoglobin that causes red blood cells to sickle under certain conditions, such as low oxygen, dehydration, or illness. Sickle cell anemia is inherited from biological parents and is not contagious. It is not caused by a person’s diet, exercise, or lifestyle. Different inherited hemoglobin combinations can cause different forms of sickle cell disease.

ConditionInherited gene patternTypical health effects
Sickle cell anemiaUsually two hemoglobin S copies (HbSS), or another disease-causing combination such as HbS with beta thalassemiaSymptoms are expected and may include anemia, pain crises, infections, and other complications.
Other sickle cell disease typesHemoglobin S combined with another abnormal hemoglobin, such as HbC or beta thalassemiaSymptoms vary by subtype and may be milder or similar to sickle cell anemia.
Sickle cell traitOne hemoglobin S copy and one usual hemoglobin A copy (HbAS)Most people have no symptoms of sickle cell disease or anemia, but they can pass the trait to children.

Risk Factors

Risk Factors for Sickle Cell Anemia

  • Inheriting disease-causing hemoglobin variants from both biological parents is the main risk factor for sickle cell anemia.
  • Having a biological parent with sickle cell disease or sickle cell trait increases the chance of inheriting a disease-causing hemoglobin variant.
  • Having a family history of sickle cell disease increases the likelihood that a child may inherit a related hemoglobin variant.
  • Having parents who both carry sickle cell trait can increase the chance that a child will have sickle cell disease.

Sickle cell gene variants are more common among people with ancestry from regions including sub-Saharan Africa, the Caribbean, the Middle East, the Mediterranean, South Asia, and Central or South America. However, people of any racial or ethnic background can have sickle cell disease. This is why family history and newborn screening are more useful than assumptions based on appearance or race; can white people get sickle cell? Yes, although the condition is less common in some populations.

Complications

Sickle Cell Anemia Complications

  • Acute chest syndrome can cause chest pain, coughing, fever, and trouble breathing and requires urgent care.
  • Stroke can occur when blocked or damaged blood vessels affect the brain.
  • Serious infections can develop, particularly when spleen function is reduced.
  • Kidney problems may develop after repeated sickling-related blood vessel injury.
  • Vision problems can occur when blood flow to the retina is affected.
  • Gallstones can form because of repeated red blood cell breakdown.
  • Pulmonary hypertension can raise pressure in the blood vessels of the lungs.
  • Chronic pain may persist between acute sickle cell crises.

Diagnosis

How Sickle Cell Anemia Is Diagnosed

Many cases are identified through routine newborn screening, often before symptoms begin. Older children and adults may be tested because of symptoms, a family history, or an affected parent. Follow-up testing confirms whether a person has sickle cell disease, another hemoglobin condition, or sickle cell trait.

  • Hemoglobin analysis by electrophoresis or a similar method identifies hemoglobin S and other hemoglobin types.
  • A complete blood count checks for anemia and provides information about the number and size of blood cells.
  • A blood smear may be used when needed to examine the shape and appearance of red blood cells.
  • Genetic testing can clarify the specific gene variants when blood test results are uncertain or detailed family information is needed.

Treatment & Management

Sickle Cell Anemia Treatment and Management

PREVENTIVE MANAGEMENT

Ongoing care may include hematology follow-up, recommended vaccinations, infection-prevention measures, hydration guidance, and medicines that reduce sickling or complications. Disease-modifying treatment, such as hydroxyurea or other specialist-prescribed medicines, is selected according to the person’s needs.

ACUTE CRISIS CARE

Pain or another crisis is treated with an individualized plan that may include fluids when appropriate, prescribed pain relief, oxygen when needed, and urgent evaluation for complications. Chest symptoms, severe anemia, stroke symptoms, or infection may require hospital treatment.

Advanced and potentially curative treatments

Blood transfusions may treat severe anemia or help prevent certain complications. A hematopoietic stem cell transplant can potentially cure sickle cell disease for some people, but it has serious risks and requires a suitable donor. Newer gene-based therapies may be appropriate for selected patients at specialized centers. Treatment decisions depend on disease type, age, complications, pregnancy status, donor availability, access to treatment, and specialist assessment. Do not start, stop, or change medicines without speaking with the care team.

Outlook and Prognosis

Outlook and Prognosis for Sickle Cell Anemia

Sickle cell anemia is usually lifelong, but consistent preventive care and modern treatments can reduce crises and complications. Many people with sickle cell disease can attend school, work, and live active lives while following an individualized care plan. Ongoing monitoring is important because health needs can change over time.

  • Disease subtype can affect the severity and pattern of symptoms.
  • The frequency and severity of pain crises can influence long-term health.
  • Organ complications, such as kidney, lung, brain, or eye problems, can affect outlook.
  • Preventive care, including vaccinations and routine monitoring, can reduce avoidable complications.
  • Response to medicines and other treatments can influence disease control.
  • Access to specialist sickle cell care can affect prevention, early treatment, and support.

When Should You See a Doctor

When Should You See a Doctor?

SEEK EMERGENCY CARE

Do not wait during serious symptoms

Use emergency services for severe or unusual pain, chest pain, trouble breathing, sudden weakness or confusion, a seizure, severe headache, high fever, marked abdominal swelling, or signs of severe dehydration. These symptoms may indicate a serious sickle cell crisis or another emergency and should not wait for routine care.

  • Contact the sickle cell care team promptly if pain is worsening or not responding to the prescribed plan.
  • Contact the care team for a fever, even if other symptoms seem mild.
  • Contact the care team for repeated vomiting or an inability to drink enough fluid.
  • Contact the care team for new vision changes.
  • Contact the care team for persistent or worsening fatigue.
  • Contact the care team when symptoms do not improve under the patient’s crisis plan.

Follow your individualized sickle cell action plan and keep regular hematology and primary care appointments, even when you feel well. Keep an updated list of medicines and emergency instructions available for yourself or your child.

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