Sickle Cell Disease

Question 1

At what point in gestation does production of HbF start to decrease?

Answer 1

32-36 weeks

Question 2

What is the ratio of HbF and HbA at birth?

Answer 2

50:50

Question 3

At what age does HbF stop being produced very much?

Answer 3

6 months

Question 4

What is the abnormal haemoglobin variety called in sickle cell disease?

Answer 4

HbS

Question 5

What type of genetic condition is sickle cell? E.g. dominant

Answer 5

Autosomal recessive

Question 6

Where is the mutation found for sickle cell disease?

Answer 6

Abnormal gene for beta globin on chromosome 11

Question 7

What is sickle cell trait?

Answer 7

Person only has 1 copy of defected gene
Carrier
Asymptomatic

Question 8

In Which ethnic groups are sickle cell disease more common? (4)

Answer 8

Africa
India
Middle East
Caribbean

Question 9

What is the relation of sickle cell disease to malaria?

Answer 9

Patients with sickle cell trait have reduced severity of malaria .: more likely to survive and pass gene on

Selective advantage

Question 10

When is sickle cell disease screened for?

Answer 10

Newborn screening heel prick test at 5 days old

Question 11

What are the complications of sickles cell disease? (9)

Answer 11

• Anaemia
• Increased risk of infection
• Stroke
• Avascular necrosis in large joints such as the hip
• Pulmonary hypertension
• Painful and persistent penile erection (priapism)
• Chronic kidney disease
• Sickle cell crises
• Acute chest syndrome

Question 12

What is the conservative management of sickle cell disease? (3)

Answer 12

. Avoid dehydration and other triggers of crisis
. Ensure vaccines up to date (pneumococcal every 5 years)
• Antibiotic prophylaxis to protect against infection with penicillin V (phenoxymethypenicillin)

Question 13

What drugs are used in the treatment of sickle cell disease? (2)

Answer 13

Hydroxycarbamide
Crizanlizumab

Question 14

How does hydroxycarbamide manage sickle cell disease?

Answer 14

• Hydroxycarbamide can be used to stimulate production of fetal haemoglobin (HbF). Fetal haemoglobin does not lead to sickling of red blood cells. This has a protective effect against sickle cell crises and acute chest syndrome.

Question 15

How does crizanlizumab manage sickle cell?

Answer 15

Crizanlizumab is a monoclonal antibody that targets P-selectin. P-selectin is an adhesion molecule found on endothelial cells on the inside walls of blood vessels and platelets. It prevents red blood cells from sticking to the blood vessel wall and reduces the frequency of vaso-occlusive crises.

Question 16

What are some triggers of sickle cell crises? (4)

Answer 16

Infection
Dehydration
Cold
Significant life events

Question 17

What is included in the management of sickle cell crises? (6)

Answer 17

• Have a low threshold for admission to hospital
• Treat any infection
• Keep warm
• Keep well hydrated (IV fluids may be required)
• Simple analgesia such as paracetamol and ibuprofen
• Penile aspiration in priapism

Question 18

What is Vaso-occlusive crisis?

Answer 18

Vaso-occlusive crisis is caused by the sickle shaped blood cells clogging capillaries causing distal ischaemia.

Question 19

What is Vaso-occlusive crisis associated with? (3)

Answer 19

Sickle cell
Dehydration
Raised haematocrit

Question 20

What can Vaso-occlusive crisis cause in males?

Answer 20

Priapism = blood trapped in penis causing painful and persistent erection

Question 21

How is priapism managed?

Answer 21

Aspiration of blood from the penis

Question 22

What is a splenic sequestration crisis?

Answer 22

Splenic sequestration crisis is caused by red blood cells blocking blood flow within the spleen. This causes an acutely enlarged and painful spleen.

Question 23

What can a splenic sequestration crisis lead to? (2)

Answer 23

Severe anaemia
Hypovolaemic shock

Question 24

What is the management of splenic sequestration crisis? (2)

Answer 24

Blood transfusion for anaemia
Fluid resuscitation for shock

Question 25

What is used to prevent splenic sequestration crises?

Answer 25

Splenectomy

Question 26

What can recurrent splenic sequestration crises lead to?

Answer 26

Splenic infarction leading to hypospleniwm

Question 27

Which bacteria are most common in hyposplenism caused by splenic sequestration crisis?

Answer 27

Encapsulated bacteria

Strep pneumoniae
Haemophilias influenzae

Question 28

What is an aplastic crisis?

Answer 28

Aplastic crisis describes a situation where there is a temporary loss of the creation of new blood cells

Question 29

What is aplastic crises triggered by?

Answer 29

Parvovirus b19

Question 30

What is the management of aplastic crisis?

Answer 30

Blood transfusions
Resolves spontaneously in a week

Question 31

What does acute chest syndrome present with?

Answer 31

Fever and respiratory symptoms

Question 32

What is seen on a cxr in acute chest syndrome?

Answer 32

New infiltrates

Question 33

What can acute chest syndrome be caused by?

Answer 33

This can be due to infection (e.g. pneumonia or bronchiolitis) or non-infective causes (e.g. pulmonary vaso-occlusion or fat emboli).

Question 34

What is the management of acute chest syndrome?(6)

Answer 34

Analgesia
Iv fluids if required
○ Antibiotics or antivirals for infections
○ Blood transfusions for anaemia
○ Incentive spirometry using a machine that encourages effective and deep breathing
○ Artificial ventilation with NIV or intubation may be required