Haematology Flashcards

1
Q

What is the haematocrit?

A

Volume % of RBCs in blood

Useful when looking for polycythaemia

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2
Q

What is the mean corpuscular haemoglobin (MCH)?

A

Mean Hb quantity in RBCs - effects colour ‘chromic’

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3
Q

Causes of microcytic anaemia?

A

Iron deficiency

Thalassemia

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4
Q

Causes of normocytic anaemia?

A

Blood loss
Anaemia of chronic disease
Haemolytic anaemia
Sickle cell

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5
Q

Causes of macrocytic anaemia?

A

B12/folate deficiency (megaloblastic)

Alcohol, pregnancy, liver disease, hydroxycarbamide, hypothyroidism

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6
Q

What is haptoglobin?

A

Acute phase marker of RBC destruction. Normally binds to free Hb so may be severely reduced in haemolysis

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7
Q

4 drugs that cause agranulocytosis

A
4 'c's 
Carbimazole
Carbemazepine
Colchicine
Clozapine
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8
Q

What is a TIBC? (Total iron binding capacity)

A

Looks at how many binding sites are available on transferrin.
Low - seen in Fe overload
High - seen in anaemia

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9
Q

What does TSAT show?

A

Should be about 30%
If high then Fe overload
If low then anaemia

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10
Q

Features of haemolytic anaemia

A

Increased RBC breakdown (raised BR, raised LDH, raised urobilinogen, reduced haptoglobin, pigmented gallstones)

Increased RBC production (increased reticulocytes)

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11
Q

3 reasons for abnormality in inherited haemolytic anaemia

A

Membrane defect
Enzyme abnormality
Hb abnormality

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12
Q

Examples of membrane problems in HA

A

Hereditary spherocytosis

Heridatary elliptocytosis

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13
Q

Examples of membrane problems in HA

A

G6PD deficiency

Pyruvate kinase deficiency

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14
Q

Hereditary spherocytosis

A

Disorder of spectrin
RBCs lose shape in circulation, they become rounded so harder to carry o2 - destroyed by extravascular system
Variable anaemia + jaundice

Film: spherocytes with no central pallor and small

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15
Q

Which condition do fava beans cause anaemia in?

A

G6PD deficiency

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16
Q

G6PD deficiency

A

G6PD only source of NADPH in RBC so only protection from oxidative stress
When oxidative stress (infections, fava beans, drugs) - cause anaemia + a non-spherocytic anaemia

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17
Q

Clinical features of G6PD deficiency

A
Anaemia
Reticulocyte count may be high
Urinalysis may show urobilinogen
Elevated UC BR 
High LDH
Low haptoglobin 

Smear shows - blister + ghost cells

18
Q

What are bite cells?

A

Seen in G6PD deficiency
Caused by the removal of Hb by the spleen

Evidence that a Heinz body has been formed then removed by the spleen

19
Q

What are Heinz bodies?

A

Precipitated, denatured Hb. Round towards the periphery.

Seen in: G6PD deficiency, unstable Hb disorder etc

20
Q

Types of acquired haemolytic anaemia

A

Auto-immune (warm or cold)
Allo-immune
Drug induced

21
Q

Warm haemolytic anaemia

A

IgG ABs against RBC with max activity at 37C

RBCs get opsonised in reticuloendothelial system

22
Q

Cold haemolytic anaemia

A

IgM ABs against RBC with max activity at 4C

IgM can bind more than 1 RBC as pentamic therefore causes clumping

23
Q

Which HA is associated with IgG ABs against RBCs?

A

Warm

24
Q

Which HA is associated with IgM ABs against RBCs?

A

Cold

25
Q

What do you give the mum to prevent haemolytic disease of the newborn?

A

Anti-RhD antibodies after 1st birth if mum rhesus -ve and baby rhesus +ve

26
Q

Examples of an allo-immune HA?

A

Haemolytic disease of the newborn

Following incompatible blood transfusion

27
Q

Features of a DVT?

A
Unilateral leg pain
Asymmetrical leg swelling
Increased temperature 
Dilatation/distension of superficial veins 
Red/discoloured skin
28
Q

Risk factors for a DVT

A

Pregnancy, cancer, COCP, major surgery, immobilisation

29
Q

Wells score for DVT

A
Cancer
Calf swelling >3cm
Swollen unilateral superficial veins
Tenderness along deep system
Unilateral pitting oedema
Bedridden >3d or surgery >12w
Paralysis, paresis or recent cast
Previous DVT 
Swelling of entire leg 
Other diagnosis just as likely
30
Q

Investigation of a DVT

A

Do a wells score
If <2 then D-dimer - if positive then USS Doppler
If 2-9 - USS Doppler

31
Q

Treatment of DVT

A

Start LMWH (enoxaparin 1.5mg/kg SC) and start warfarin. When INR is 2-3 stop LMWH and continue warfarin for 3-6m

32
Q

What raises a D-dimer?

A
Liver disease
Inflammation
Malignancy
Pregnancy
Recent surgery
33
Q

Wells score for PE

A
Previous DVT/PE
Cancer
Clinical signs of DVT
Immobilisation/recent surgery
Haemoptysis
HR >100
Alternative diagnosis less likely 
<4 = low risk - D-dimer
>4 = high risk - CTPA + LMWH
34
Q

What do PT and INR look at?

A

The extrinsic path (Factor 7)

Should be 12secs = INR of 1
Aim for INR of 2-3 if on warfarin

35
Q

What does APTT look at?

A

Intrinsic path

Should be <40s

36
Q

What does bleeding time look at?

A

Platelet function

37
Q

What does thrombin time look at?

A

Fibrinogen test - time it takes to convert fibrinogen to fibrin. Tests the common path

Should be <11secs

38
Q

Which is the intrinsic path?

A

Surface contact - 12 - 11 - 9

39
Q

Which is the extrinsic path?

A

Tissue factor - 7

40
Q

Which is the common path?

A

10 - (prothrombin - thrombin) - (fibrinogen - fibrin)

41
Q

What are platelet type bleeds?

A

Involve skin + mucous membranes

42
Q

What are factor type bleeds?

A

Involve deep tissue + joints