Sickle Cell Disease

Question 1

What are the clinical features of HbS?

Answer 1

Chronic haemolytic anaemia
Painful vasoocclusive crises
Increased susceptibility to infection
Chronic organ damage
Increased mortality

Question 2

What is seen on the blood film of HbS?

Answer 2

Nucleated red cells
Irreversibly sickled red cells
Nuclear remnants

Question 3

What are the consequences of the abnormalities seen on the blood film?

Answer 3

They have a shortened lifestyle as they haemolyse

Free Hb is released into the circulations and cause endothelial damage leading to upregulation of HOX1 to remove them

Question 4

What are the main types of sickle cell disease?

Answer 4

Sickle cell anaemia: homozygous HbSS
SC disease: HbS, HbC
Sickle B0thalassemia: SB0thal
Sickle B+thalassemia: SB+thal

Question 5

What is the pathogenesis of a vasoocclusion?

Answer 5

Sickle cells upregulate adhesion molecules, these cause thrombosis which can occur in microvasculature
Platelets are activated
Endothelial cells produces fewer vasodilatory molecules
Leucocytes are activated with increased adhesion and this leads to vasoocclusion and pain

Question 6

What happens to free haem in the circulation?

Answer 6

It scvenges NO, this means that ROS which are normally mopped up by NO are not cleared and there is increased reactive damage - sickling is worse

(Rees et al 2010)

Question 7

What is the management of Sickle cell disease?

Answer 7

Good diagnosis and screening, education and support
Early penicillin to prevent childhood death
Analgesia
Blood transfusion
HbF augmenting agents
Haemopoietic stem cell transplant/gene therapy

Question 8

How is recurrent acute chest sndrome treated?

Answer 8

Hydroxycarbamide
Chemotherapy increases the level of HbF
Reduces incidence of painful crises and ACS

Question 9

In transfusion of sickle cell what percentage should HbS be kept under?

Answer 9

Under 30%

Question 10

What is transfusion in sickle cell used for?

Answer 10

To prevent the recurrence of stroke