Haemoglobin disorders

Question 1

Normal haemoglobin

Answer 1

HbA = 2x alpha and 2x beta - 98% in adults

HbA2 = 2x alpha and 2x delta - 2-3%

HbF = 2x alpha and 2x gamma - neonates

Question 2

Alpha Thalassaemia summary

Answer 2

Reduced alpha globin production
–> reduced HbA, HbA2 and HbF

4 genes -
-> 3 disease states - Trait, HbH disease and hydrops fetalis

Trait = 2 or more functioning genes = clinically silent

China and South-east Asians

Question 3

HbH disease

Answer 3

HbH disease = 1 functioning copy of alpha gene

Chronic haemolysis and splenomegaly   
Low Hb 
Low MCV
HbH cells on BF
HbH on HPLC
Confirm with gene studies

Question 4

Beta Thalassaemia summary

Answer 4

Reduced beta globin production
–> reduced HbA

2 beta genes
–> 2 disease states - minor/trait and major

Mediterranaean and South East Asians

Question 5

Beta Thalassaemia Minor

Answer 5

Reduced HbA with compensatory increase in HbA2

Clinically asymptomatic

Mild anaemia on film - low MCV and MCH
Target cells on film
HPLC = increased Hb A2 and Hb F

Question 6

Beta thalassaemia Major

Answer 6

Absent or severe deficiency of HbA

Requires transfusions from 3-6 months

Haemolysis
BM expansion
Extra medullary haemopoeisis
Developmental delay

Severe Hb loss - 30-70
Low MCV and MCH
anisopoikilocytosis
HPLC –> elevated HbA2 and Hb F no HbA

Treatment:

• transfusions
• Fe chelation
• Autologous SCT
• Endocrine and bone and thrombotic disease

Question 7

Sickle cell Anaemia pathogenesis

Answer 7

Changes of GAG to GTG on the beta globin gene

• -> HbS
• -> HbS polymerises into long fibres on deoxygenation
• -> distorted sickle like erythrocyte

Autosomal recessive disease - need 2 copies of HbS for disease

African heritage

Treatment:

• Hydroxyurea
• Transfusion

Question 8

Sickle cell disease presentation?

Answer 8

Vaso-occulsion disease most common

Acute chest syndrome
Haemolysis

SICKLE CRISIS
Can be triggered by parvovirus

Question 9

Most common side effect of blood transfusion?

Answer 9

Circulatory overload

Question 10

Other side effects of blood transfusion?

Answer 10

ABO incompatibility - clinical error at the bedside

Bacterial contamination
Transfusion acquired infections