Anemia drepanocítica is the Spanish and Portuguese name for sickle cell anemia, an inherited blood disorder in which red blood cells contain an abnormal hemoglobin that makes them bend into a stiff sickle shape. These cells break down early, causing chronic anemia, and they block small blood vessels, causing pain and organ damage. Management rests on prevention, prompt treatment of crises, disease-modifying medicines and, for some patients, curative transplant or gene therapy.
The condition is most common in people with ancestry from sub-Saharan Africa, the Mediterranean, the Middle East, India and parts of Latin America. This guide follows the disease from the single gene change that causes it through to the treatments used in clinic today. For a broader introduction, see our sickle cell guide.
The Mechanism: From One Gene Change to Sickled Cells
Normal adult hemoglobin, hemoglobin A (HbA), is made of two alpha and two beta globin chains. In anemia drepanocítica, a single-letter change in the beta-globin gene (HBB) swaps one amino acid, glutamic acid, for another, valine, at position 6. The result is hemoglobin S (HbS).
When HbS gives up its oxygen, the molecules stick together into long, rigid polymers. These fibers distort the red cell into a crescent or sickle shape. Early on the change can reverse when the cell picks up oxygen again, but repeated cycles damage the cell membrane until the cell stays permanently sickled.
Why sickled cells cause harm
- Hemolysis: sickled cells survive only about 10 to 20 days, compared with about 120 days for normal red cells. This constant destruction causes anemia and jaundice.
- Vaso-occlusion: stiff, sticky cells lodge in small vessels together with white cells and platelets, cutting off blood flow and causing pain and tissue injury.
- Vessel damage: hemoglobin released from broken cells mops up nitric oxide, a natural vessel relaxant, which contributes to inflammation and narrowed arteries over time.
Inheritance and Crisis Triggers
Sickle cell disease is autosomal recessive. A person with two HbS genes (HbSS) has sickle cell anemia. A person with one HbS gene and one normal gene has sickle cell trait (HbAS) and is usually healthy, but can pass the gene on. When both parents carry the trait, each pregnancy has a one-in-four chance of a child with the disease.
| Genotype | Name | Typical severity |
|---|---|---|
| HbAS | Sickle cell trait | Usually no symptoms; a carrier state |
| HbSS | Sickle cell anemia | Usually the most severe form |
| HbS/beta-zero thalassemia | Sickle beta-zero thalassemia | Similar to HbSS |
| HbSC | Hemoglobin SC disease | Often milder anemia, but eye and bone problems are common |
| HbS/beta-plus thalassemia | Sickle beta-plus thalassemia | Usually milder |
Anything that lowers oxygen, thickens the blood or causes inflammation can bring on sickling. Common triggers include dehydration, infection, cold exposure, strenuous exercise, high altitude, stress and alcohol.
Clinical Picture and Complications
Symptoms often begin at around 6 months of age, as protective fetal hemoglobin (HbF) falls. Young children may develop painful swelling of the hands and feet (dactylitis). The best-known feature is the vaso-occlusive crisis, an episode of severe pain in the bones, chest, back or abdomen. Day to day, patients live with chronic anemia, tiredness, pale skin and yellowing of the eyes.
Major complications
- Acute chest syndrome: chest pain, fever and a new shadow on the chest X-ray; a medical emergency.
- Stroke: especially in children, which is why yearly transcranial Doppler screening is recommended from age 2.
- Infections: the spleen is damaged early in life, raising the risk of serious bacterial infections.
- Splenic sequestration and aplastic crisis: sudden, severe drops in hemoglobin in children.
- Chronic organ damage: kidney disease, eye disease (retinopathy), leg ulcers, priapism, avascular necrosis of the hip and pulmonary hypertension.
Diagnosis and Newborn Screening
A complete blood count shows anemia, usually with a high reticulocyte count as the marrow tries to keep up. The blood film may show sickled cells and target cells. The definitive test is hemoglobin electrophoresis or high-performance liquid chromatography (HPLC), which identifies and measures HbS, HbF and other variants. DNA testing can confirm the genotype and is used in prenatal diagnosis. The workup differs from that of anemia caused by marrow failure, described in our guide to the diagnosis of anemia in children with aplastic anemia.
Many countries screen all newborns using a few drops of blood from a heel prick. Early diagnosis means infants can start penicillin prophylaxis and vaccinations, and parents can learn to recognize fever, pallor and a swelling spleen before a crisis becomes dangerous.
Management: Prevention, Crises and Disease Modification
Everyday prevention
Core care includes daily penicillin in early childhood, full vaccinations (including pneumococcal and meningococcal vaccines), folic acid, good hydration and avoiding known triggers. Regular reviews check blood counts, kidneys, eyes and lungs.
Treating a pain crisis
Pain crises need fast, adequate pain relief, often with opioids in hospital, alongside fluids and treatment of any infection. Encouraging deep breathing with incentive spirometry helps prevent acute chest syndrome.
Disease-modifying medicines
Hydroxyurea is the cornerstone. It raises HbF, which dilutes HbS and reduces polymerization, lowering the frequency of pain crises and acute chest syndrome. It is now offered from infancy in many guidelines. L-glutamine and crizanlizumab are other approved options in some countries. Voxelotor, which blocked HbS polymerization, was withdrawn from the market in 2024 over safety concerns.
Transfusion and cure
Blood transfusions treat severe anemia and are given regularly to children at high stroke risk; long-term transfusion requires iron chelation to prevent iron overload. Hematopoietic stem cell transplantation from a matched sibling can cure the disease. Gene therapies, including a CRISPR-based treatment that switches HbF production back on, have been approved in some countries, but access, cost and the need for high-dose chemotherapy limit their use.
Key Takeaways
- Anemia drepanocítica is caused by a single change in the beta-globin gene that produces hemoglobin S.
- HbS polymerizes when deoxygenated, causing hemolysis, blocked vessels and chronic organ damage.
- Diagnosis rests on hemoglobin electrophoresis or HPLC, and newborn screening allows early preventive care.
- Hydroxyurea, infection prevention and prompt crisis care form the basis of management; transplant and gene therapy can be curative for selected patients.
Frequently Asked Questions
Is anemia drepanocítica the same as sickle cell disease?
Anemia drepanocítica usually refers to sickle cell anemia (HbSS), the most common and often most severe form. “Sickle cell disease” is the broader term that also includes HbSC and sickle beta-thalassemia. The mechanisms and management are largely shared.
Can people with sickle cell trait get sick?
Most people with the trait live normal, healthy lives. Rarely, problems can occur under extreme conditions such as severe dehydration, very intense exercise or high altitude. The main importance of the trait is for family planning.
When should someone with sickle cell anemia go to the hospital?
Seek urgent care for a fever of 38.5°C (101.3°F) or higher, chest pain or breathlessness, severe pain not controlled at home, sudden weakness or speech problems, a rapidly enlarging spleen in a child, or a painful erection lasting more than a few hours. These can signal life-threatening complications.
Is there a cure?
Stem cell transplantation and newer gene therapies can cure the disease in selected patients. Both carry significant risks and are not available everywhere, so most people are managed long term with hydroxyurea and preventive care.
