Red Cell Enzyme Defects ✅

Question 1

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

Answer 1

Glucose-6-phosphate dehydrogenase (G6PD)

Question 2

What does G6PD protect against?

Answer 2

Protects the cell from oxidative damage

Question 3

What does G6PD do?

Answer 3

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

Question 4

What is the inheritance of G6PD deficiency?

Answer 4

X-linked

Question 5

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

Answer 5

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

Question 6

Who is G6PD deficiency most prevalent in?

Answer 6

Patients of African, Mediterranean, or Asian origin

Question 7

Are patients with G6PD deficiency always symptomatic?

Answer 7

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

Question 8

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

Answer 8

Neonatal jaundice

Question 9

Is the neonatal jaundice caused by G6PD deficiency severe?

Answer 9

Potentially, can be severe enough to cause kernicterus

Question 10

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

Answer 10

Liver dysfunction, rather than haemolysis

Question 11

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

Answer 11

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

Question 12

How does G6PD deficiency present after the neonatal period?

Answer 12

Usually as an acute haemolytic crisis

Question 13

What can precipitate an acute haemolytic crisis in G6PD deficiency?

Answer 13

• Infection
• Certain drugs
• Ingesting broad beans

Question 14

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

Answer 14

• Reduced Hb
• Raised reticulocytes
• Hyperbilirubinaemia
• Increased LDH

Question 15

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

Answer 15

• Fragmented red cells
• ‘Bite’ cells
• Polychromasia

Question 16

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

Answer 16

Heinz bodies

Question 17

What are Heinz bodies?

Answer 17

Red cell inclusions made up of denatured Hb

Question 18

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

Answer 18

Completely normal

Question 19

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

Answer 19

No

Question 20

What is the treatment for G6PD deficiency?

Answer 20

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

Question 21

How is diagnosis confirmed in G6DPD deficiency?

Answer 21

By measuring red cell G6PD levels

Question 22

When might red cell G6PD levels be falsely elevated?

Answer 22

During an acute crisis

Question 23

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

Answer 23

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

Question 24

How common is pyruvate kinase deficiency compared to G6PD deficiency?

Answer 24

Much less common

Question 25

When should pyruvate kinase deficiency be considered?

Answer 25

In presence of family history, or after excluding G6PD deficiency

Question 26

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

Answer 26

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

Question 27

How might pyruvate kinase deficiency present?

Answer 27

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

Question 28

Is the level of anaemia variable in pyruvate kinase deficiency?

Answer 28

Yes

Question 29

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

Answer 29

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

Question 30

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

Answer 30

Patients can be transfusion dependent

Question 31

What is the inheritance pattern of pyruvate kinase deficiency?

Answer 31

Autosomal recessive

Question 32

What is found on the blood film in pyruvate kinase deficiency?

Answer 32

'Prickle' red cells

Question 33

How can a diagnosis of pyruvate kinase deficiency be made?

Answer 33

Measuring pyruvate kinase enzyme levels Usually necessary to test affected child and their parents to confirm the diagnosis

Question 34

What happens in autoimmune haemolytic anaemia (AIHA)?

Answer 34

An antibody against a persons own red cells is produced

Question 35

What can AIHA be divided into?

Answer 35

Warm and cold types

Question 36

What is the difference between warm and cold AIHA?

Answer 36

In warm, antibody binds most strongly at 37 degrees | In cold, binds most strongly at 4 degrees

Question 37

What antibody is usually involved in warm AIHA?

Answer 37

IgG

Question 38

What antibody is usually involved in cold AIHA?

Answer 38

IgM

Question 39

When does AIHA most commonly present in children?

Answer 39

During intercurrent infection

Question 40

What normally happens when AIHA occurs during intercurrent infection?

Answer 40

It resolves spontaneously

Question 41

What might AIHA occur in association with?

Answer 41

- Another immunological disorder, such as SLE or juvenile idiopathic arthritis (JIA) - Lymphoproliferative disorder, such as Hodgkin's lymphoma

Question 42

How is a diagnosis of AIHA confirmed?

Answer 42

- Characteristic blood film - Haemolysis profile - Positive DAT

Question 43

What is a haemolysis profile?

Answer 43

- Unconjugated hyperbilirubinaemia - Raised LDH - Increased reticulocytes - Reduced haptoglobin levels

Question 44

What might be required in causes of AIHA that do not resolve spontaneously?

Answer 44

Immunosuppressive treatment, such as steroids, azathioprine, or cyclosporin