AKT · Haematology/Anaemia & red cell

Sickle cell disease

Autosomal recessive HbS (β-globin Glu→Val) → red-cell sickling, vaso-occlusion and haemolysis

Overview

An autosomal recessive haemoglobinopathy (HbSS) in which a β-globin point mutation produces haemoglobin S that polymerises when deoxygenated, sickling red cells and causing chronic haemolysis and vaso-occlusive crises. Affects people of African/Caribbean (and Mediterranean/Middle-Eastern/Indian) ancestry. Detected on newborn screening; management is prophylaxis (penicillin, vaccines, hydroxycarbamide) plus prompt crisis treatment. (Paediatric detail is on child_health.)

Recognise

Painful vaso-occlusive crises (bones, chest, abdomen), often triggered by cold, dehydration, infection, hypoxia; chronic haemolytic anaemia, jaundice, gallstones; splenic sequestration/autosplenectomy → hyposplenism
Acute CHEST SYNDROME (fever, chest pain, hypoxia, new infiltrate) — a leading cause of death; stroke; priapism; aplastic crisis (parvovirus B19)
Blood film: sickle cells, target cells, Howell-Jolly bodies (hyposplenism); confirmed on haemoglobin electrophoresis

Red flags

Acute chest syndrome (hypoxia + new infiltrate) → emergency (oxygen, analgesia, antibiotics, transfusion/exchange)
Stroke, splenic sequestration (rapidly enlarging spleen + falling Hb), aplastic crisis, or sepsis (hyposplenic) → emergencies

Differentials & how to tell them apart

Sickle cell trait (HbAS)usually asymptomatic carrier; sickling only in extreme hypoxia

Thalassaemiamicrocytic; different electrophoresis pattern

Other causes of bone/abdominal painbut in a known sickle patient, treat as a crisis and exclude chest syndrome/sepsis

Sickle cell disease — sickled red cells on the blood film
Prof. Osaro Erhabor / CC BY-SA 3.0 — Wikimedia Commons

Investigations

Newborn screening; haemoglobin electrophoresis/HPLC (confirms HbSS); FBC + reticulocytes + blood film (sickle cells, Howell-Jolly bodies); during a crisis — assess for infection/hypoxia/chest syndrome (CXR, ABG); cross-match if transfusing.

Management

Crisis → analgesia + O2 + hydration + treat infection; prophylaxis (penicillin/vaccines) + hydroxycarbamide

1Confirm on electrophoresis (HbSS). Treat a vaso-occlusive crisis promptly with strong analgesia, oxygen, hydration and treatment of any infection.Gate: Acute chest syndrome (hypoxia + new infiltrate), stroke, splenic sequestration or aplastic crisis are emergencies needing urgent transfusion/exchange; functional hyposplenism mandates penicillin prophylaxis + vaccines.
2Long-term: hydroxycarbamide (raises HbF, fewer crises), folic acid, penicillin prophylaxis and vaccines, trigger avoidance; transfusion programmes/transplant in selected patients. Full paediatric detail on child_health.

Acute crisis: analgesia (often opioids), oxygen, hydration, treat infection; transfusion/exchange for severe crises — prompt strong analgesia; exchange transfusion for chest syndrome/stroke

Prophylaxis: penicillin V + vaccines (pneumococcal/Hib/meningococcal) — hyposplenism — lifelong infection prophylaxis (functional asplenia)

Hydroxycarbamide — raises HbF, reduces crisis frequency and chest syndrome — disease-modifying

Folic acid; avoid triggers; transfusion/transplant in selected cases — manage gallstones, leg ulcers, retinopathy, priapism; curative stem-cell transplant in some children

Key points

HbSS + vaso-occlusive crises + chronic haemolysis in a patient of African/Caribbean ancestry = sickle cell disease → crisis: analgesia + O2 + hydration + treat infection. Emergencies: ACUTE CHEST SYNDROME (transfuse/exchange), stroke, splenic sequestration, aplastic crisis (parvovirus). Hyposplenic → penicillin + vaccines; hydroxycarbamide is disease-modifying.

Monitor & prognosis

Crisis frequency, Hb/reticulocytes, chest syndrome/stroke surveillance, hydroxycarbamide response, prophylaxis adherence.

Improved with comprehensive care; chest syndrome, stroke and sepsis are the leading causes of death.

Source: BSH sickle cell; cross-ref child_health (sickle/screening), pharmacology (hydroxycarbamide)