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Flashcards in Sickle Cell Disease Deck (28)
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1

Recall the prevalence of SCA in the UK?

Most prevalent monogenic disorder in UK

2

What is genotype that produces full SCA?

HbS HbS

3

Recall two compound heterozygous states of sickle cell disease

1. SC (C is another structural variant of HbC)
2. S-beta-thalassaemia = HbS and beta thalassaemia

4

Recall the variance of symptoms in sickle cell anaemia

Even those with same genotype can be clinically heterogenous

5

What does the term "sickle cell disease" refer to?

Any disease state that results from sickling

6

Recall the 2 pathogenesis pathways that lead to anaemia in sickle cell disease

1. Shortened red-cell lifespan --> haemolysis
2. Reduced erythropoietic drive due to HbS having a low O2 affinity

7

What is the difference between HbA and HbS?

Glutamic acid replaced by a valine at position 6

8

Other than anaemia, what 2 pathologies are often seen in sickle cell disease as a direct result of shortened red cell lifespan?

Gall stones
Aplastic crisis

9

What is an aplastic crisis and what is its most likely cause?

Temporary cessation of erythropoiesis
Parvovirus B19

10

What are the 3 categories of pathology seen in sickle cell disease?

Haemolysis
Blockage to microvascular circulation
Limited NO availability

11

What are the 3 main effects of microvascular circulation being blocked in sickle cell disease, and what are the subsequent effects of these?

Pain, dysfuction adn tissue necrosis
Necrosis --> bone disorders, skin ulceration and hyposplenism (due to repeated vaso-occlusive damage)

12

What is the main effect of NO availability being limited in sickle cell disease? What causes availability to be low?

Pulmonary hypertension
Low due to NO being free in plasma following haemolysis

13

When do symptoms of sickle cell disease first present and why?

Around 6 months when transition is made between HbF and HbA

14

What are the 3 primary early manifestations of sickle cell disease?

Dactylitis
Splenic sequestration
Infection

15

What is splenic sequestration?

Sudden acute pooling of blood in spleen

16

What sort of infection is commonly seen in early sickle cell disease and why?

Pneumococcal - this is an encapsulated bacteria and so more likely to occue in SCD as there is hyposplenism

17

Recall 3 later-stage manifestations of sickle cell disease (pre-crisis)

Stroke
Gall stones
The acute chest syndrome

18

Why is the risk of gallstones increased in sickle cell disease?

Co-inheritance of Gilbert syndrome

19

What is the acute chest syndrome?

Vaso-occlusive crisis of pulmonary vasculature

20

Recall 4 symptoms of sickle cell emergencies

Septic shock
Cerebral haemorrhage
Hypoxia
Priapism

21

Recall the 2 main consequences sickling of red cells

Dehydration of cells
Increased adherence to vascular endothelium

22

What is the main feature of sickle cell disease shown by an FBC

High reticulocytes

23

What 4 structures can be identified on a blood film that is positive for sickle cell disease

Sickled cells (obviously)
Boat cells
Target cells
Howell-Jolly bodies

24

What is the first test done in suspected sickle cell disease and how does it work?

Solubility test: in the presence of a reducing agent ocyHb --> Hb causing solubility to decrease and solution to become turgid

25

What method is used to definitively diagnose sickle cell disease?

HPLC

26

Recall 2 preventative measures used in sickle cell disease?

Prophylactic penicillin for encapsulated bacteria infection risk
Train parents to examine abdomen for splenomegaly

27

What supplement is given in sickle cell disease, and why?

Folic acid
Supplies folate for haematopoiesis

28

Name and explain the mechanism of action of a drug used to treat sickle cell disease

Hydroxyurea: introduces HbF into blood to prevent sickling