Anaemia 2

Question 1

what is anaemia caused by marrow failure called?

Answer 1

aplastic anaemia

Question 2

how is aplastic anaemia defined?

Answer 2

pancytopenia with hypocellularity (aplasia- defective development) of the BM

reduction in number of pluripotential stem cells + a fault in those remaining/immune reaction against them

Question 3

aetiology aplastic anaemia

Answer 3

variety of disorders

drugs e.g. chemo

Question 4

clinical features aplastic anaemia

Answer 4

anaemic
increased suceptilibity to infection + bleeding

bruising, bleeding gums and epistaxis

Question 5

Ix aplastic anaemia

Answer 5

blood count: pancytopenia. low/absent reticulocytes

BM examination: hypocellular marrow with increased fat spaces

Question 6

Mx aplastic anaemia

Answer 6

withdrawal of the offending agent
supportive care
some form of definitive therapy: BM transplant, immunosuppressive therapy

Question 7

What are inherited haemolytic anaemias due to?

Answer 7

defects in one or more components of the mature RBC:

• cell membrane
• haemoglobin
• metabolic machinery of the RBC

Question 8

What is sickle cell anaemia?

Answer 8

group of inherited RBC disorders, caused by HbS

autosomal recessive. Cr11 single base point-mutation

type of normocytic anaemia

Question 9

in SSA, what causes the red cell to deform into sickle shape?

Answer 9

deoxygenated HbS polymerises into rod-like aggregates

Question 10

characteristics of sickle cells

Answer 10

fragile, have decreased lifespan and occlude vessels

after repeated sickling the red cell membranes lose their flexibility + are sickled

dehydrated, dense + dont return to normal when oxygenated

Question 11

malaria and sickle cell

Answer 11

heterozygote carriers are protected

Question 12

when do HbSS pts present?

Answer 12

~2yrs when they’ve lost most of their HbF and virtually all Hb is HbS

Question 13

what is sickling precipitated by?

Answer 13

infection, dehydration, cold, acidosis and hypoxia

Question 14

acute complications of sickle cell

Answer 14

painful crisis, sickle acute chest syndrome, stroke

Question 15

chronic complications of sickle cell

Answer 15

renal impairment, pulm HTN, joint damage

Question 16

how does ss affect the spleen?

Answer 16

splenic sequesteration.

vaso-occlusion –> acute painful enlargement of the spleen. pooling of blood. organomegaly, severe anaemia and shock, hypotension

Question 17

acute chest syndrome (part of faso-occlusive crisis) and ssa

Answer 17

pulm infiltrates involving complete segments of lung

• due to fat, embolism from necrotic BM, or infection with chlamydia

Question 18

long term affects SSA

Answer 18

impaired growth + development
bones: common site for V-O episodes –> chronic infarcts
leg ulcers
neurological

Question 19

Ix SSA

Answer 19

peripheral blood film

**Hb electrophoresis = definitive Dx, single HbS band seen and no normal HbA

Question 20

Mx SSA

Answer 20

?Blood transfusion

Hydroxycarbamide if frequent crises: long term increases production of HbF

Antibiotic prophylaxis + immunisation as splenic infarct –> hyposplenism –> increases susceptibility to infection

Question 21

What is thalassaemia

Answer 21

disorders of the globin - the globular chain part of Hb

cause is inherited gene mutation, varies between types

Question 22

beta-thalassaemia

Answer 22

no normal/stable beta chains are produced of they are at a reduced number

Question 23

what causes bizarre Hb in beta-thalassemia?

Answer 23

excess alpha chains combine with whatever other chains are around

Question 24

presentation of minor beta-thalassemia

Answer 24

carrier- found in heterozygous state. mild/asymptomatic

Question 25

presentation of intermediate beta-thalassemia

Answer 25

symptomatic with moderate anaemia

excessive iron absorption can occur due to impaired erythropoiesis

Question 26

presentation of major beta-thalassemia

Answer 26

Cooley’s anaemia
homozygous b-thal.

Presents in 1st year of life (lack of Hbf)

failure to thrive, infection, severe anaemia, splenomegaly + bone expansion

Question 27

Mx beta thalassemia

Answer 27

suppress ineffective erythropeosis

folic acid supplements
regular blood transfusions
splenectomy?

Question 28

How to avoid iron overload which may occur

Answer 28

iron chelating agents e.g. desferrioxamine

ascorbic acid supplements - allow for increased urinary excretion of iron in tandem with desferrioxamine

Question 29

alpha thalassemia

Answer 29

reduced alpha chain synthesis

4, 3, 2, and 1-gene deletions
- declining in severity of clinical presentation

Question 30

what is the enzyme glucose-6-phosphate dehydrogenase vital in?

Answer 30

the hexose monophosphate shunt, which maintains glutathione in the reduced state

glutathione protects against oxidant injury in the red cell

Question 31

what is G6PD deficiency?

Answer 31

a common heterogeneous X-linked trait

Question 32

what does G6PD cause?

Answer 32

neonatal jaundice
chronic haemolytic anaemia
acute haemolysis

Question 33

what are precipitating factors in G6PD?

Answer 33

eating fava beans
common drugs such as:
- quinine
- sulphonamides
- quinolone
- nitrofurantoin

Question 34

Dx G6PD

Answer 34

direct measurement of enzyme levels in the red cell

Question 35

Tx G6PD

Answer 35

avoidance of precipitation factors

transfusion if necessary

Question 36

haemolysis

Answer 36

normal or increased RBC production but decreased lifespan to

Question 37

in haemolytic anaemia, increased haem turnover –> what?

Answer 37

anaemia and jaundice

there is often splenomegaly: (excess urinary bilirubin)

• decreased Hb
• increased reticulocytes
• +ve coombs test

Question 38

causes of haemolytic anaemia

Answer 38

sickle cell
thalassaemia
+others

acquired:

• immune autoantibodies against RBC
• mechanical