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Haematology > Exam 1- red blood cells > Flashcards

Exam 1- red blood cells Flashcards

1
Q

Where is EPO secreted from and in response to what?

A

Cortical interstitial cells of kidney; hypoxaemia

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2
Q

What is the role of 2,3 BPG?

A

Promotes release of oxygen from Hb at low oxygen concentration

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3
Q

What is the role of glutathione? In what condition is there a lack of reduced glutathione?

A

Protects against toxic effects of reactive oxygen species. Glucose 6 phosphate dehydrogenase deficieny

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4
Q

Means of co2 transport in blood

A

As bicarbonate ion (60%)
Bound to Hb (30%)
Dissolved in solution (10%)

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5
Q

Structure of adult Hb

A

4 protein subunits, each with a single haem group capable of binding one oxygen molecule

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6
Q

Structure of

a) adult Hb
b) foetal Hb
c) haem group

A

a) alpha 2, beta 2
b) alpha 2, gamma 2
c) porphyrin ring with central Fe atom

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7
Q

How does foetal haemoglobin differ from adult in function? ()

A

Higher affinity for oxygen

Lower affinity for 2,3 BPG

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8
Q

Causes of microcytic (low MCV) anaemia (2)

A

Iron deficiency

Thalassaemia

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9
Q

Diagnostic test for iron deficiency

A

Low serum ferritin (“storage” iron)

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10
Q

Causes of iron deficiency (3)

A

Inadequate intake
Inadequate absorption
Increased loss through haemorrhage

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11
Q

Name the transporter responsible for:

a) iron transport in the duodenum
b) iron export from enterocytes

A

a) DMT-1

b) ferroportin

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12
Q

What is reticulocytosis indicative of?

A

Increased red cell production

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13
Q

What is hereditary haemochromatosis caused by?

A

Autosomal recessive HFE mutations- causes excessive intestinal absorption of iron

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14
Q

Clinical manifestations of hereditary haemochromatosis (5)

A 
Fatigue
Joint pain
Liver cirrhosis
Diabetes
Cardiomyopathy
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15
Q

Treatment of hereditary haemochromatosis

A

Venesection 450-500ml

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16
Q

What is the underlying pathophysiology of megaloblastic macrocytic anaemia?

A

Defects in DNA synthesis and nuclear maturation due to b12/folate deficiency- these are essential co-factors in these processes

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17
Q

What is pernicious anaemia?

A

Deficiency of intrinsic factor due to autoantibodies against IF or gastric parietal cells; results in megaloblastic anaemia as a result of vitamin B12 deficiency

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18
Q

Where is the intrinsic factor-b12 complex absorbed?

A

Terminal ileum

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19
Q

How is pernicous anaemia treated?

A

B12 injections

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20
Q

Causes of folate deficiency

a) drugs
b) increased requirement
c) decreased absorption

A

a) anticonvulsants, trimethoprim
b) haemolysis, pregnancy, malignancy
c) crohns, coeliac disease, diet

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21
Q

Symptoms/signs of B12/folate deficiency (3)

A

Anaemia symptoms
Glossitis
Diarrhoea

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22
Q

Neurological problems caused by b12 deficiency (2)

A

Subacute combined degeneration of the spinal cord

Peripheral neuropathy

23
Q

What are the two main groups of haemoglobinopathies?

A

Thalassaemias- decreased production

Structural variants e.g. sickle cell haemoglobin

24
Q

How many alpha-genes need to be deleted for symptoms? What is this disease called?

A

Three out of four

Haemoglobin H disease (alpha thalassaemia), due to presence of HbH (tetramers of beta-globin)

25
Q

What are the features of Haemoglobin H disease?

A

Microcytic anaemia
Splenomegaly
Jaundice (due to haemolysis)

26
Q

How is HbH disease managed?

A

Transfusion (regularity depending on severity)

Folic acid supplementation

27
Q

What is the severest form of alpha thalassaemia?

A

Barts hydrops fetalis

28
Q

Diagnosis of alpha thalassaemia (3)

A

FBC and blood film
High performance liquid chromatography
PCR genotyping

29
Q

What is beta-thalassaemia caused by and why does it only affect Haemoglobin A(adult)

A

autosomal recessive point mutations which either inactivate or reduce function of beta-globin
because adult haemoglobin is the only one which has beta globin

30
Q

Classification of beta thalassaemia (3)

A

Trait (asymptomatic)
Intermedia (requires occassional tranfusion)
Major (lifelong dependenceon transfusion)

31
Q

What are the features of beta thalassaemia

a) blood film
b) HPLC

A

a) anisopoikilocytosis, microcytic anaemia, target cells

b) mostly HbF; elevated levels of HbA2 (alpha2 delta2)

32
Q

Clinial features of beta thal. major (3)

A

Aged 6-24 months
Failure to thrive
Extramedullary haemopoiesis- hepatosplenomegaly,bone deformity e.g. skull

33
Q

How is beta-thalassaemia treated? What is the major side effect of this and how is this managed?

A

Regular transfusion. Iron overload iron-chelating agents e.g. desferrioxamine

34
Q

What causes sickle cell anaemia?

A

Autosomal recessive point mutations in beta globin gene, creating Hb which polymerises at low [o2] causing red cell membrane distortion

35
Q

What are the consequences of red cells which sickle? (2)

A 
Tissue infarction (sickle cell crises)
Chronic haemolysis
36
Q

What are the features of a sickle crisis? (5)

A 
Bone pain
Pleuritic chest pain
CVA/seizures
Splenic infarcts
Priapism
37
Q

Precipitants of a sickle crisis (4)

A

Hypoxia
Cold
Infection
Dehydration

38
Q

Management of a sickle crisis

A

Opiates, fluids, oxygen

39
Q

Long term treatment of sickle cell anaemia (4)

A

Prophylactic penicillin
Folic acid
Vaccination against encapsulated organisms
Hydroxycarbamide (induces HbF production)

40
Q

What are the two main types of haemolysis?

A

Intravascular and extravascular

41
Q

Test results/signs which indicate haemolysis

a) serum biochemistry
b) blood film
c) full blood count
d) clinical signs

A

a) high LDH, high bilirubin (unconjugated)
b) reticulocytosis, spherocytes (extravascular) schistocytes (intravascular)
c) anaemia
d) hepatosplenomegaly

42
Q

Automal dominant condition with defects in red cell cytoskeleton

A

Hereditary spherocytosis

43
Q

In haemolytic patients infection with what virus causes an aplastic crisis?

A

Parvovirus

44
Q

Why can chronic haemolysis cause megaloblastic anaemia?

A

Folate deficiency

45
Q

Diagnostic test for hereditary spherocytosis?

A

Osmotic fragility test

46
Q

What causes G6PD deficiency?

A

X-linked recessive mutations in G6PD making them vulnerable to oxidative stress,

47
Q

Blood film results in G6PD deficiency (2)

A

Heinz bodies of denatured haemoglobin

“Bite cells” resulting from removal of denatured haemoglobin

48
Q

Precipitants of G6PD crisis; how is crisis prevented?

A

Broad beans, antimalarials, infection

Avoid precipitants

49
Q

Diagnostic test for autoimmune haemolytic anaemia

A

Direct antiglobulin test (Coombs test)

50
Q

Causes of non-megaloblastic macrocytic anaemia (4)

A

Alcohol
Liver disease
Hypothyroidism
Marrow failure

51
Q

What causes acute haemolytic transfusion reactions? Why is the response so dramatic?

A

IgM antibodies against ABO group antigens; IgM is able to activate complement cascade and the membrane attack complex

52
Q

What is often the consequence of an acute haemolytic reaction?

A

DIC and renal failure

53
Q

Cause of

a) delayed haemolytic transfusion reactions
b) febrile non-haemolytic reactions

A

a) irregularr antibodies

b) contaminating white cells/cytokines and vasoactive susbstances produced by these WBCs during storage

54
Q

Other than transfusion reactions what are the risks?

A

Circulatory overload (particularly old/heart failure)
Bacterial/viral infection
Acute lung injury (TRALI)

Haematology (25 decks)

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