Sickle Cell disease

Question 1

What is sickle cell disease?

Answer 1

When red blood cells are more easily destroyed because they are in a sickle shape
this can cause anaemia

Question 2

What is the primary haemoglobin type affected in sickle cell disease?

Answer 2

HbA - 2 alpha + 2 beta peptide chains

Foetal haemoglobin is not affected by the mutation.

Question 3

What causes sickle cell disease?

Answer 3

A mutation in the beta globin gene causing the beta chains to be misshapen

Question 4

What type of disease is sickle cell?

Answer 4

Autosomal recessive

Carriers don’t notice symptoms unless they are exposed to extreme conditions

Question 5

What is one advantage of sickle cell disease?

Answer 5

It decreases the severity of malaria

Question 6

How is sickle cell disease tested for?

Answer 6

on the newborn screening heel prick test at 5 days of age.

Question 7

What is HbS?

Answer 7

Sickle haemoglobin

• 2 alpha chains
• 2 beta (sickle) chains (Both chains have to be mutated)

Question 8

What extreme conditions can cause sickle carriers to experience symptoms?

Answer 8

High altitude
Dehydration
Low temperatures
Infection 
(All of these things can set of a sickle cell crisis)

Question 9

What happens when oxygen is bound to haemoglobin?

Answer 9

The HbS carries oxygen around perfectly well, theres no problems until the oxygen is unbound

Question 10

What happens when theres no oxygen bound to the HbS?

Answer 10

The haemoglobin changes its shape and binds to other proteins causing the red blood cell to become a present shape = sickling

Question 11

How are RBCs destroyed?

Answer 11

2/3rds are destroyed extravascularly

1/3rd is destroyed intravascularly

Question 12

Where does free haemoglobin after haemolysis go?

Answer 12

Binds to haptoglobin.

Low haptoglobin is a sign of sickle cell disease

Question 13

What does low haptoglobin show?

Answer 13

Intravascular haemolysis is occurring

Question 14

What are signs/complications of sickle cell disease?

Answer 14

Dactylitis (sickle cells getting blocked in small blood vessels in the digits)
Pain crisis
Avacsular necrosis
Increased bone formation (increased bone marrow to try and increase more RBCs)
Hepatomegaly (liver also tries to make RBCs)
Splenic infarcts
Splenomegaly
Infection
Strokes
Haematuria
Gallstones

Question 15

What investigations can be done for sickle cell disease?

Answer 15

Blood smear - shows sickle cells

Protein electrophoresis - identifies HbS

Question 16

What is the treatment for sickle cell disease?

Answer 16

Opioids
Oxygen
Fluids
Antibiotics
Folic acid
Blood transfusions (*risk of iron overload + production of antibodies against future transfusions)

Children - prophylaxis penicillin

Question 17

What is a carrier of one sickle cell gene called?

Answer 17

Sickle cell trait.

Question 18

When do symptoms of sickle cell disease begin to show?

Answer 18

Usually at 4-6 months (because this is when the foetal haemoglobin runs out and the patient relies on their HbA, which is actually HbS).

Question 19

Why are sickle cell patients more prone to bacterial infections?

Answer 19

Because the spleen is overwhelmed with too many red blood cells, meaning it cannot phagocytose as much bacteria as it usually would.

Question 20

What are the types of sickle cell crisis?

Answer 20

Vaso occlusive crisis
Acute chest syndrome
Aplastic crisis
Splenic sequestration crisis

Question 21

what is a common cause of aplastic crisis?

Answer 21

Parvovirus B19.

Question 22

What type of anaemia is sickle cell disease?

Answer 22

Microcytic anaemia.

Question 23

what is the main treatment for a sickle cell crisis?

Answer 23

Oxygen (15L via non rebreathe mask)
IV fluids 
Keep patient warm
Antibiotics
Aspiration (for priapism)
Blood transfusion (For aplastic crisis)

Refer to haematology

Question 24

What is an aplastic crisis?

Answer 24

when the bone marrow doesn’t make enough red blood cells

Question 25

what is a sequestration crisis?

Answer 25

when the spleen is enlarged due to a build up of sickle cells

Question 26

What is acute chest syndrome?

Answer 26

A vaso occlusive crisis in the lungs brought on by infection

(Fever OR Respiratory symptoms) + Infiltrates seen on CXR

Question 27

What is a vaso occlusive crisis?

Answer 27

when sickled red blood cells cause a blockage in blood flow through the vessels
(Often results in avascular necrosis of bones and organ damage).

Question 28

what is a common urogenital emergency associated with sickle cell crisis?

Answer 28

Priapism - a prolonged and painful erection of the penis. Treated by urgent aspiration