ʜaemoglobinopathies and obstetric haematology (haematology pathology)

Question 1

What is the structure and function of normal red cells (erythrocytes)ʔ

Answer 1

• Bi concave disks
• no nucleus

-Function to transport oxygen that is bound to oxygen.

Question 2

What controlls the production of ʀed blood cellsʔ

Answer 2

Erythropoietin (EPO) produced in the kidneys controls red blood cell production

Question 3

What is the structure of ʜAemoglobinʔ

Answer 3

4 globin chainsː

• 2 alpha
• 2 non alpha

Question 4

What is the haemoglobin structure in a fetusʔ

Answer 4

4 globin chainsː
2 alpha
and
2 gamma

Question 5

What is the haemoglobin structure in an adultʔ

Answer 5

4 globin chainsː
- 2 alpha and 2 delta
Oʀ
-2 alpha and 2 beta (most)

Question 6

what chromosome encodes for the alpha globin chain in haemoglobin>

Answer 6

chromosome 16

Question 7

what chromosome codes for the gamma, beta and delta globin chains in haemaglobin?

Answer 7

Chromosome 11

Question 8

What is Thalassaemia?

Answer 8

A change in globin gene expression leads to reduced rate of synthesis of normal globin chains.

The disease is caused by an imbalance of alpha to beta chain production.

Free globin chains damage red blood cell membrane

Question 9

What are the methods of maternal testing for haemoglobinopathies?

Answer 9

1) Genetic screening

2) Antenatal screening&raquo_space; can opt for termination of affected pregnancies

Question 10

What is the maximum time when haemodilution can occur in preganancy?

Answer 10

32 weeks

Question 11

During pregnancy what happens to the mean cell volume (MCV)?

Answer 11

MCV increases during pregnancy

Question 12

When does leukocytosis occur in pregnancy?

Answer 12

Neutrophilia increases from 2nd month.

A peak range of 9-15 can be seen in the 2nd-3rd trimester.

Question 13

What is gestational thrombocytopenia?

Answer 13

Platelet count falls after 20 weeks.

Thrombocytopenia occurs usually towards the end of the pregancy.

Question 14

What are the causes of thrombocytopenia in pregnancy?

Answer 14

1) folate deficiency
2) Gestational
3) Pre-eclampsia

Coincidental:

1) Viruses e.g. HIV, EBV
2) Sepsis
3) bone marrow not producing enough

Question 15

Pregnancy is a pro-thrombotic state (increased coagulation). What can be seen as evidence of this?

Answer 15

• platelet activation
• increased procoagulant factors
• reduction in anticoagulants
• reduction in fibrinolysis
• Rise in coagulation factors

Question 16

How can structural haemaglobin variants detected?

Answer 16

Haemoglobin Electrophoresis

Question 17

what characteristic of thalassaemias indicate iron deficiency?

Answer 17

small, pale red cells (hypochromic / microcytic)

Question 18

What is sickle cell disease?

Answer 18

Distortion of the red cell membrane produced a sickle shape. It is associated with haemolytic anaemia.

Caused by a Glutamine to Valine change at position 6 of the beta globin gene.

Question 19

What are the acute complications of sickle cell disease?

Answer 19

1) Vaso-occlusive crisi. ( the cells stick together to block vessels)&raquo_space;>Ischaemic
2) Septicaemia
3) Aplastic crisis (RBC production decreased)
4) Sequestration crisis of spleen and liver due to trapping of RBCs, makes the organs larger.

Question 20

What are the chronic complications of sickle cell disease?

Answer 20

1) Hyposplenism (due to infarction and atrophy of spleen)
2) Renal damage (sickle shaped cells cause tubular and glomerular damage)»>renal failure.
3) Avascular necrosis of femoral and humeral heads (blood vessels blocked by sickle cells)
4) Leg ulcers, retinopathy, osteomyelitis, gall stones

Question 21

What is the treatment of sickle cell disease?

Answer 21

1) Penicillin
2) hydration (to maintain red cell water)
3) Transfusion
4) Respiratory - oxygen
5) Avascular necrosis - joint replacement
6) bone marrow transplant

Question 22

What causes beta-thalassaemia?

Answer 22

1) reduced rate of production of beta-globin chains.

Question 23

What is the difference between beta-thalassaemia minor, intermedia and major?

Answer 23

MINOR:
-total Hb level normal / slightly reduced&raquo_space;no clinical problems.

INTERMEDIA:

• Pulmonary hypertension
• Bone changes (osteoporosis)
• leg ulcers

MAJOR:

• severe anaemia at 1 to 2 years.
• lots of nucleated RBCs
• More RBCs produced to compensate.
• stunted growth
• enlarged liver / spleen

Question 24

What is the pathalogical basis of beta thalassaemia major?

Answer 24

1) Excess of alpha chains.
2) innefective RBC production and shortened RBC lifespan.»>ANAEMIA
3) Increased marrow activity leads to stunted growth, increased iron absorption, organ damage, protien malnutrition.
4) Enlarged and over-active spleen

Question 25

How is beta-thalassaemia major treated?

Answer 25

1) Transfusion
2) Iron chelation therapy (to avoid iron overload)
3) Bone marrow transplant