Red Cell Enzyme Defects Flashcards Preview

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Flashcards in Red Cell Enzyme Defects Deck (44)
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1

What is the most common red cell enzyme deficiency causing haemolytic anaemia?

Glucose-6-phosphate dehydrogenase (G6PD)

2

What does G6PD protect against?

Protects the cell from oxidative damage

3

What does G6PD do?

Catalyses the first step of the pentose phosphate pathway, regulating the rate of the pathway

4

What is the inheritance of G6PD deficiency?

X-linked

5

What is the result of G6PD deficiency being a X-linked disorder?

It predominantly affects boys, although female carriers may be mildly affected

6

Who is G6PD deficiency most prevalent in?

Patients of African, Mediterranean, or Asian origin

7

Are patients with G6PD deficiency always symptomatic?

No, majority of patients are asymptomatic most of the time, although some rare mutations can cause chronic haemolytic anaemia

8

What is one of the most common presentations of G6PD deficiency?

Neonatal jaundice

9

Is the neonatal jaundice caused by G6PD deficiency severe?

Potentially, can be severe enough to cause kernicterus

10

What is thought to be the cause of the jaundice in G6PD deficiency?

Liver dysfunction, rather than haemolysis

11

What blood results support the theory that the jaundice in G6PD deficiency is predominantly due to liver dysfunction rather than haemolysis?

Despite marked hyperbilirubinaemia, the Hb is usually normal or very slightly reduced

12

How does G6PD deficiency present after the neonatal period?

Usually as an acute haemolytic crisis

13

What can precipitate an acute haemolytic crisis in G6PD deficiency?

- Infection
- Certain drugs
- Ingesting broad beans

14

What will blood tests during an acute haemolytic crisis due to G6PD deficiency show?

- Reduced Hb
- Raised reticulocytes
- Hyperbilirubinaemia
- Increased LDH

15

What will be showed on blood film in acute haemolysis caused by G6PD deficiency?

- Fragmented red cells
- 'Bite' cells
- Polychromasia

16

What can be seen on blood film in acute haemolysis caused by G6PD deficiency if special stains are used?

Heinz bodies

17

What are Heinz bodies?

Red cell inclusions made up of denatured Hb

18

What does the blood film show in G6PD deficiency between haemolytic crises?

Completely normal

19

Is the reticulocyte count increased in G6PD deficiency between haemolytic crises?

No

20

What is the treatment for G6PD deficiency?

Treatment is unnecessary apart from during severe haemolytic episodes, were red cell transfusion may be required

21

How is diagnosis confirmed in G6DPD deficiency?

By measuring red cell G6PD levels

22

When might red cell G6PD levels be falsely elevated?

During an acute crisis

23

What advice should be given after a diagnosis of G6PD deficiency?

Parents and children should be advised about avoiding potential triggers, and given a list of the most commonly used drugs which may precipitate acute haemolysis

24

How common is pyruvate kinase deficiency compared to G6PD deficiency?

Much less common

25

When should pyruvate kinase deficiency be considered?

In presence of family history, or after excluding G6PD deficiency

26

What does a deficiency of pyruvate kinase in RBCs result in?

Insufficient ATP production, leading to 'rigid' cells and subsequent haemolysis

27

How might pyruvate kinase deficiency present?

- Hydrops fetalis
- Neonatal haemolytic anaemia
- Chronic haemolytic anaemia in early childhood

28

Is the level of anaemia variable in pyruvate kinase deficiency?

Yes

29

Why is the anaemia surprisingly well tolerated in pyruvate kinase deficiency?

Because increased 2,3-DPG levels shift the O2 dissociation curve to the right

30

What can be required in severe causes of pyruvate kinase deficiency?

Patients can be transfusion dependent