Sickle Cell Disease (2)

Question 1

What is it?

What are the effects of RBCs being sickle-shaped?

What type of Hb do these pts have?
→ What is the most common and severe type of this?
→ What are the other types that can occur?

Who is it more common in?

Answer 1

➊ Autonomic recessive genetic condition that causes sickle-shaped RBCs

➋ * More fragile and easily destroyed, therefore leading to Haemolytic Anaemia
* More likely to occlude small vessels

➌ HbS
→ HbSS (homozygous)
→ Coinheritance of HbS with other haemoglobin variants, such as HbC or β-thalassaemia, leading to the HbSC or HbS-βthal forms of sickle cell disease. These tend to be a milder version of sickle-cell.

➍ Afro-Caribbeans

Question 2

What are its main complications?

Answer 2

• Anaemia (haemolytic) - Jaundice
• Sickle cell crises
• Acute chest syndrome
• Pulmonary HTN
• Increased risk of infection
• CKD
• Avascular necrosis
• Stroke

Question 3

Sickle Cell Crises:
When can it occur?

What is the most common type of crises?
→ What occurs here?
→ What is it associated with?
→ What can it lead to?

What is Acute Chest Syndrome?
→ How is it diagnosed?

What is Splenic Sequestration Crisis?
→ What is often done in recurrent cases?
→ What blood results are seen here?

What is Aplastic Crisis?
→ What is this typically triggered by?
→ What blood results are seen here?

How are these crises managed?

Answer 3

➊ Spontaneously or triggered by stresses e.g. infection, dehydration, cold or significant life events

➋ Vaso-occlusive Crisis (AKA painful crisis)
→ Occlusion of vessels → Distal ischaemia, which is incredibly painful
→ Dehydration and raised haematocrit
→ Priapism

➌ Severe type of vaso-occlusive crisis – Infarction of lung parenchyma
→ Fever/respiratory symptoms + New infiltrates on CXR

➍ Blocked blood flow to spleen → Enlarged, painful spleen → Severe anaemia and Hypovolaemic shock
→ Splenectomy
→ Low Hb + raised reticulocyte count

N.B. Remember that the bone marrow is what produces reticulocytes. As long as it’s working, reticulocytes will be produced as a response to haemolytic anaemia.

➎ Temporary loss of RBC production → Anaemia
→ Parvovirus B19 (Causes slapped cheek syndrome – red rash cheeks, spotty rash on torso and limbs)
→ Low Hb + low reticulocyte count

➏ Supportively as there’s no treatment – Analgesia, Abx, Warmth, Hydration

Question 4

Investigations:
What will be seen on blood tests?

What will a blood film show?

What is needed for a definitive diagnosis?

Answer 4

➊ Microcytic anaemia (reticulocytosis and unconjugated hyperbilirubinemia may also be noted)

➋ Sickle cells, target cells, reticulocytosis, features of functional hyposplenism (Howell-Jolly bodies, nucleated red blood cells)

➌ Hb electrophoresis +/- genetic testing

Question 5

Management:
What is typically the first main thing to give these pts?

What are the other things involved in managing these pts?

Which medication can be given in special, chronic cases? How does it work?

Answer 5

➊ Opioid analgesia

➋ * Avoid dehydration and other triggers
* Prophylactic Abx
* Red cell transfusion
* Be up to date with vaccinations
* Bone marrow transplant

➌ Hydroxycarbamide – stimulates production of HbF