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# Sickle cell disease

An inherited hemoglobin disease in which red cells bend into a sickle shape, block vessels and cause pain, anemia and organ damage.

Updated 2026-11-01

## Structures involved

Tap one to see what it is and open it in 3D.

- [Spleen](https://durgical.com/en/anatomy/spleen/)
- [Kidneys](https://durgical.com/en/anatomy/kidney/)
- [Gallbladder](https://durgical.com/en/anatomy/gallbladder/)
- [Femoral head cartilage](https://durgical.com/en/anatomy/articular-cartilage-of-femoral-head/)
- [Femur](https://durgical.com/en/anatomy/femur/)
- [Right lower lobe](https://durgical.com/en/anatomy/inferior-lobe-of-right-lung/)
- [Left lower lobe](https://durgical.com/en/anatomy/inferior-lobe-of-left-lung/)
- [Middle cerebral artery](https://durgical.com/en/anatomy/middle-cerebral-artery/)

## In biochemistry

- [Glycated haemoglobin (HbA1c)](https://durgical.com/en/biochemistry/topics/glycated-haemoglobin/)
- [Newborn screening](https://durgical.com/en/biochemistry/topics/newborn-screening/)
- [Chromatography](https://durgical.com/en/biochemistry/topics/chromatography/)
- [Lactate dehydrogenase (LDH) as a lab marker](https://durgical.com/en/biochemistry/topics/lactate-dehydrogenase-as-a-lab-marker/)
- [Heme oxygenase](https://durgical.com/en/biochemistry/enzymes/heme-oxygenase/)
- [Iron metabolism](https://durgical.com/en/biochemistry/topics/iron-metabolism/)
- [Hemoglobin variants (HbA, HbA2, HbF, HbS, HbC)](https://durgical.com/en/biochemistry/topics/hemoglobin-variants/)
- [Types of mutations](https://durgical.com/en/biochemistry/topics/types-of-mutations/)
- [Gene therapy](https://durgical.com/en/biochemistry/topics/gene-therapy/)
- [CRISPR-Cas9 and genome editing](https://durgical.com/en/biochemistry/topics/crispr-cas9-and-genome-editing/)
- [Protein structure and folding](https://durgical.com/en/biochemistry/topics/protein-structure-and-folding/)
- [Oxygen binding: haemoglobin versus myoglobin](https://durgical.com/en/biochemistry/topics/oxygen-binding-haemoglobin-versus-myoglobin/)

## In immunology

- [Spleen: white pulp, red pulp, asplenia](https://durgical.com/en/immunology/spleen-white-pulp-red-pulp-asplenia/)
- [Transfusion reactions](https://durgical.com/en/immunology/transfusion-reactions/)
- [Secondary immunodeficiency: HIV, malnutrition, drugs, asplenia](https://durgical.com/en/immunology/secondary-immunodeficiency-hiv-malnutrition-drugs-asplenia/)

## In histology

- [Blood cells on a smear: erythrocytes, leukocytes, platelets](https://durgical.com/en/histology/blood-cells-on-a-smear-erythrocytes-leukocytes-platelets/)
- [Lymph node and spleen under the microscope](https://durgical.com/en/histology/lymph-node-and-spleen-under-the-microscope/)

## In the clinical exam

- [Anemia syndrome](https://durgical.com/en/clinical-exam/anemia-syndrome/)

## In physiology

- [Anemia physiology and compensation](https://durgical.com/en/physiology/anemia-physiology-and-compensation/)
- [The red cell life cycle and the spleen](https://durgical.com/en/physiology/the-red-cell-life-cycle-and-the-spleen/)

## Why it happens

- [Pigments in tissue: lipofuscin, hemosiderin, melanin, bilirubin, carbon](https://durgical.com/en/general-pathology/pigments-in-tissue-lipofuscin-hemosiderin-melanin-bilirubin-carbon/)
- [Mendelian inheritance: autosomal dominant, recessive and X-linked](https://durgical.com/en/general-pathology/mendelian-inheritance-autosomal-dominant-recessive-and-x-linked/)
- [Hypercoagulable states: inherited and acquired](https://durgical.com/en/general-pathology/hypercoagulable-states-inherited-and-acquired/)
- [Infarction: red vs white, and what decides the damage](https://durgical.com/en/general-pathology/infarction-red-vs-white-and-what-decides-the-damage/)
- [Causes of cell injury](https://durgical.com/en/general-pathology/causes-of-cell-injury/)

## What it is

A group of hemoglobinopathies with HbS (β6 Glu→Val): HbSS (sickle cell anemia), HbSC and HbS/β-thalassemia. Autosomal recessive inheritance.

## Who gets it

It is the most common severe hemoglobinopathy in the world, especially in sub-Saharan Africa. In Colombia the trait and the disease are more common in Afro-descendant communities of the Pacific and Caribbean coasts.

## Causes

- Two abnormal HBB alleles, at least one carrying HbS

## Risk factors

- Both parents carriers (1-in-4 risk per pregnancy)
- Crisis triggers: dehydration, cold, infection, hypoxia, altitude, extreme exercise

## Pathophysiology

When deoxygenated, HbS polymerises into fibres that deform and stiffen the red cell. Sickled cells are destroyed (hemolysis, 10–20-day lifespan) and stick to the endothelium with leucocytes and platelets, blocking the microcirculation: ischaemia, pain and infarcts. Hemolysis releases hemoglobin that consumes nitric oxide and harms vessels. Repeated infarcts shrink the [spleen](https://durgical.com/en/anatomy/spleen/) (autosplenectomy).

## Classification

- HbSS: the most severe form
- HbS/β⁰-thalassemia: similar to HbSS
- HbSC and HbS/β⁺-thalassemia: milder
- Trait (HbAS): carrier, almost always without symptoms

## Symptoms and signs

- Crises of severe pain in bones, chest or [abdomen](https://durgical.com/en/anatomy/region/abdomen/)
- Painful swelling of hands and feet in infants (dactylitis)
- Pallor, fatigue and jaundice
- Frequent infections
- Delayed growth and puberty
- Prolonged painful erection (priapism)

## Red flags

- Fever of 38.5 °C or more (risk of pneumococcal sepsis)
- Chest pain, cough and hypoxaemia (acute chest syndrome)
- One-sided weakness, speech disturbance or seizure (stroke)
- Rapidly enlarging spleen with marked pallor (splenic sequestration)
- Priapism lasting more than 4 hours

## Diagnosis

**Clinical**
Chronic hemolytic anemia with pain crises in someone with a family history; ideally detected by newborn screening.

**Tests**
Hemoglobin electrophoresis, HPLC or isoelectric focusing (predominant HbS, no HbA in HbSS); blood count with high reticulocytes; smear with sickle cells and Howell-Jolly bodies; high indirect bilirubin and LDH; genetic testing.

**Imaging**
Annual transcranial Doppler from age 2 to 16 to detect stroke risk; [chest](https://durgical.com/en/anatomy/region/chest/) X-ray in acute chest syndrome; hip MRI for avascular necrosis; ultrasound for gallstones.

## Treatment

**Acute**
Pain crisis: prompt analgesia (including opioids), hydration and oxygen if hypoxaemic

**Medical**
Hydroxyurea, which raises HbF and reduces crises, acute chest syndrome and transfusions

**Medical**
Prophylactic penicillin in childhood and full vaccination, including pneumococcal

**Procedure**
Simple or exchange transfusion in stroke, severe acute chest syndrome and primary stroke prevention

**Procedure**
Hematopoietic stem cell transplantation, curative in selected cases; gene therapies are new options

**Follow-up**
Monitoring iron in transfused patients, [kidney](https://durgical.com/en/anatomy/kidney/) function, [retina](https://durgical.com/en/anatomy/retina/) and echocardiography

## Drugs for this condition

- [Pneumococcal vaccine](https://durgical.com/en/pharmacology/pneumococcal-vaccine/)

## Complications

- Childhood stroke
- Acute chest syndrome and pulmonary hypertension
- Functional asplenia and severe infections; Salmonella osteomyelitis
- Avascular necrosis of the femoral head
- Renal papillary necrosis and chronic kidney disease
- Pigment gallstones
- Leg ulcers and retinopathy

## Prognosis

With newborn screening, prophylaxis and hydroxyurea most children reach adulthood, although life expectancy remains reduced.

## Prevention

- Newborn screening and genetic counselling for carrier couples

## Test yourself

Think of the answer, then tap the question to see it.

## Which mutation produces HbS?

Glutamic acid replaced by valine at position 6 of β-globin (HBB gene).

## Why do people with sickle cell anemia get more pneumococcal infections?

Repeated infarcts destroy the spleen (autosplenectomy), removing defence against encapsulated bacteria.

## Which study is used in children to prevent stroke?

Transcranial Doppler: high velocities indicate risk and lead to regular transfusions.

## Why is sickle cell trait common in malaria regions?

Carriers are protected against severe P. falciparum malaria.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/conditions/sickle-cell-disease/)

## Related conditions

- [Thalassemias (α and β)](https://durgical.com/en/conditions/thalassemias/)
- [Neonatal jaundice](https://durgical.com/en/conditions/neonatal-jaundice/)
- [Gallstones (cholelithiasis)](https://durgical.com/en/conditions/gallstones/)
- [Malaria](https://durgical.com/en/conditions/malaria/)
- [Ischaemic stroke](https://durgical.com/en/conditions/ischaemic-stroke/)
- [Avascular necrosis of the femoral head](https://durgical.com/en/conditions/avascular-necrosis-of-the-femoral-head/)
- [Chronic kidney disease](https://durgical.com/en/conditions/chronic-kidney-disease/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Sickle cell disease: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/sickle-cell-disease/) (MedlinePlus, US National Library of Medicine, 2026); [Sickle cell disease: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000527.htm) (MedlinePlus, US National Library of Medicine, 2026); [HBB gene: MedlinePlus Genetics](https://medlineplus.gov/genetics/gene/hbb/) (MedlinePlus, US National Library of Medicine, 2026); [Sickle Cell Disease | Sickle Cell Anemia | MedlinePlus](https://medlineplus.gov/sicklecelldisease.html) (MedlinePlus, US National Library of Medicine, 2026).

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Source: https://durgical.com/en/conditions/sickle-cell-disease/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/sickle-cell-disease/