Sickle cell disease: crisis types, management and hydroxyurea
RezzySickle cell disease (SCD) is a massive topic for the UKMLA AKT. It’s essentially a story of what happens when a single amino acid substitution (glutamic acid to valine) turns flexible red blood cells into rigid, "sickle-shaped" troublemakers.
When these cells get stuck, they cause various types of crises. I've put together a quick breakdown of the main ones you'll need to recognize in a clinical vignette.
| Crisis Type | Key Features | Clinical Clues |
|---|---|---|
| Vaso-occlusive (VOC) | Most common; "Painful crisis." | Severe pain in bones/joints; triggered by cold, dehydration, or infection. |
| Acute Chest Syndrome | A life-threatening VOC in the lungs. | Fever, cough, chest pain, and new infiltrates on CXR. |
| Splenic Sequestration | Blood pools in the spleen. | Sudden splenomegaly, drop in Hb, and signs of hypovolemic shock. |
| Aplastic Crisis | Sudden halt in RBC production. | Triggered by Parvovirus B19; look for a very low reticulocyte count. |
| Hemolytic Crisis | Rapid breakdown of RBCs. | Sudden drop in Hb with an increase in jaundice/bilirubin. |
When it comes to management, the AKT loves to test the NICE guidelines for acute crises. The golden rule for a painful VOC is to provide analgesia within 30 minutes of arrival.
Acute Management (The "ABCDE" Approach):
- Analgesia: Use a stepwise approach (paracetamol/NSAIDs, but often requires strong opioids like morphine).
- Hydration: IV or oral fluids to prevent further sickling.
- Oxygen: Only if $O_2$ sats are $< 95%$.
- Antibiotics: If there's any suspicion of infection (remember, these patients are functionally asplenic).
- Transfusion: Simple or exchange transfusion is indicated in severe cases like Acute Chest Syndrome or Stroke.
Let me pull up a visual of what these sickled cells actually look like under the microscope—it makes it much easier to visualize why they cause so much trouble in the microvasculature.
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