Red Cells

Question 1

Describe red cell breakdown

Answer 1

Occurs in reticuloendothelial system
- macrophages in spleen, liver, lymph nodes, lungs etc.

Globin; AAs reutilised

Haem; iron recycled into haemoglobin, haem –> biliverdin –> bilirubin

Bilirubin bound to albumin in plasma

Question 2

Describe hereditary spherocytosis

Answer 2

Most common form is autosomal dominant

Defects in 5 different structural proteins

• ankkyrin
• alpha spectrin
• beta spectrin
• band 3
• protein 4.2

Clinical presentation variable; anaemia, jaundice (neonatal), splenomegaly, pigment gallstones

Treatment; folic acid, transfusion, splenectomy if anaemia severe

Question 3

What are some rare membrane disorders?

Answer 3

Hereditary elliptocytosis
Hereditary Pyropoikilocytosis
South East Asian Ovalocytosis

Question 4

What does the pentose phosphate shunt do?

Answer 4

Prevent red cells from oxidative damage

G6PD

• produces NADPH; vital for reduction of glutathione
• reduced glutathione scavenges and detoxifies reactive oxygen species

Question 5

Describe G6PD deficiency (info)

Answer 5

Commonest disease causing enzymopathy in world

Cells vulnerable to oxidative damage

Confers protection against malaria (most common in malarial areas)

X linked; affects males, female carriers

Question 6

Describe the presentation G6PD deficiency

Answer 6

Variable clinical presentation

• variable degrees of anaemia
• neonatal jaundice
• splenomegaly
• pigment gallstones

Drug, broad been or infection precipitated jaundice and anaemia; intravascular haemolysis, haemoglobinuria

Question 7

What are triggers to haemolysis in G6PD deficiency?

Answer 7

Infection
Acute illness i.e. DKA
Broad beans

Drugs; antimalarials, sulphonamides and sulphones, antibacterials, analgesics, antihelminthics

Question 8

Describe pyruvate kinase deficiency

Answer 8

Reduced ATP, increased 2,3-DPG, cells rigid

Variable severity; anaemia, jaundice, gallstones

Question 9

What causes the oxygen curve to shift right?

Answer 9

Reduced pH
Increased DPG
Increased temp
Increased CO2

Question 10

What causes the oxygen curve to shift left?

Answer 10

Increased pH
Reduced DPG
Reduced temp
HbF; higher O2 affinity than HbA

Question 11

What is the structural problem in thalassaemia?

Answer 11

reduced or absent globin chain production

- alpha, beta, delta, gamma

Question 12

Describe normal adult haemoglobins

Answer 12

a - alpha, b - beta d - delta, y - gamma

HbA; 97% aabb

HbA2; 2% aadd

HbF; 1% aayy

Question 13

Describe sickle haemoglobin HbS

Answer 13

Haem molecule + 2 alpha chain and 2 beta (sickle) chains

Point mutation with autosomal recessive inheritance

Question 14

What is the inheritance of thalassemia?

Answer 14

Autosomal recessive

Question 15

What are clinical presentations of sickle cell disease?

Answer 15

Painful Vasoocclusive crises; bone

Chest crisis
Stroke
Increased infection risk

Chronic haemolytic anaemia

Question 16

How should a painful crisis in sickle cell be treated?

Answer 16

Often requires opiates; within 30mins of presentation, avoid pethidine

Hydration, oxygen, consider antibiotics

Question 17

Management of sickle cell disease long-term

Answer 17

Vaccination
Penicillin (and malarial) prophylaxis

Folic acid

Question 18

Management of acute sickle cell events

Answer 18

Hydration
Oxygenation
Prompt infection treatment
Analgesia; opiates, NSAIDs
Blood transfusion

Question 19

What disease modifying drugs are available for sickle cell anaemia?

Answer 19

hydroxycarbamide

Question 20

Describe beta thalassaemia major

Answer 20

No beta chains, transfusion dependent anaemia

Severe anaemia

• present 3-6months
• expainsion ineffective bone marrow (hair on end appearance)
• bony deformities
• splenomegaly
• growth retardation

Question 21

Describe beta thalassaemia major treatment

Answer 21

Chronic transfusion support 4-6weekly
- normal growth and development but iron overloading

Must treat iron overloading
- iron chelation therapy

Bone marrow transplant curative