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2a Haematology > Macrocytotic Anaemia > Flashcards

Macrocytotic Anaemia Flashcards

1
Q

What is INR?

A

International Normalised Ratio
Prothrombin time
Coagulation speed through the extrinsic pathway

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2
Q

What is the coagulation speed through the intrinsic pathway called?

A

APTT (Activated Partial Thromboplastin Time)

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3
Q

What is the normal range for INR?

A

0.8-1.2

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4
Q

What is the normal INR on warfarin?

A

2-3

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5
Q

What is warfarin?

A

Anticoagulant (blood thinner), inhibiting the action of vitamin K, reducing production of clotting factors

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6
Q

What is the normal range for APTT?

A

35-45 seconds

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7
Q

What is the normal range for APTT if on heparin?

A

60-80 seconds

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8
Q

What is heparin?

A

Anticoagulant (blood thinner), enhances activity of antithrombin III which inhibits blood clotting

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9
Q

What is the bleeding time or thrombin time?

A

Time for for fibrinogen to convert to fibrin in presence of thrombin

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10
Q

What is a normal thrombin time?

A

12-14 seconds

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11
Q

What is the order of factors involved in the intrinsic cascade ?

A

12, 11, 9, 8,

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12
Q

What does MCV stand for?

A

Mean Corpuscular Volume (of a RBC)

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13
Q

What does MCV of >95 mean?

A

Macrocytosis (can be megaloblastic or non-megaloblastic)

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14
Q

What is the difference between megaloblastic or non-megaloblastic anemia?

A

Both anaemias occur in presence of macrocytosis.
Megaloblastic anaemia is when the RBCs also have hyper-segmented nucleated neutrophils.
Non-megaloblastic anaemia is when there aren’t hyper-segmented nucleated neutrophils.

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15
Q

What causes megaloblastic anaemia? (macrocytosis and hyper-segmented neutrophils)

A

B12 deficiency
Folate deficiency

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16
Q

What is B12?

A

Water soluble vitamin, needed for RBC formation, involved in DNA synthesis, has role in health of nervous system, involved in metabolism of fatty acids and amino acids.
Found in meat, fish, dairy and fortified cereals. Vegans should take supplement.

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17
Q

How long does the body store B12 for?

A

3 years

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18
Q

B12 is absorbed in the…

A

terminal ileum

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19
Q

What must B12 bind to?

A

Intrinsic factor

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20
Q

Where is intrinsic factor made?

A

The parietal cells in the gastric body and fundus

21
Q

What is the type of megaloblastic anaemia caused by vitamin B12 deficiency?

A

Pernicious anaemia

22
Q

How exactly is there a B12 deficiency in pernicious anaemia?

A

Body attacks parietal cells resulting in reduction in intrinsic factor production. Therefore, little B12 can bind as be absorbed. This leads to megaloblast formation.

23
Q

What are effects of pernicious anaemia

A

Pallor or in sever cases Lemon yellow skin (jaundice),
Angular stomatitis,
Glossitis
Fatigue,
SOB,
Neurological symptoms due to demyelination:
Symmetrical paraesthesia (tingling/numbness in hands and feet)
Muscle weakness
Altered mental status

24
Q

How is pernicious anaemia treated?

A

Hydroxycolbamin (B12 tablets)
Potentially B12 injections
Dietary advice to eat salmon and eggs

25
Q

What are causes other than pernicious anaemia of B12 deficiency?

A

Malnutrition
Pregnancy
Crohn’s disease (affects ileum)
Gastrectomy
Bariatric surgery

26
Q

Before binding to IF in duodenum and being absorbed in the ileum, what does B12 bind with in the saliva?

A

transcobalamin

(B12 is also called cobalamin)

27
Q

What are common symptoms in deficiency of B12, folate or Fe?

A

Angular stomatitis (cracked sores at corner of mouth)
Glossitis (inflammation of tongue)

28
Q

What is the differential between folate deficiency and B12 deficiency?

A

B12 deficiency causes demyelination so shows neurological symptoms and can cause jaundice, whereas folate deficiency doesn’t

29
Q

What investigations would you take in suspected pernicious anaemia?

A

FBC
Blood film
To look for serum B12 and presence of anti-parietal antibodies or anti-IF antibodies and to see macrocytic, hyper-segmented nucleated neutrophils.

30
Q

More lobes in a neutrophils means it is less mature because…

A

As DNA matures, it becomes more compacted and highly wound round histones.

31
Q

What are the 2 types of deficiencies that cause megaloblastic anaemia?

A

B12 and folate

32
Q

How long does it take for pernicious anaemia to develop?

A

Years (because B12 is stored for 3 years)

33
Q

How long does it take for folate deficiency anaemia to develop?

A

Months

34
Q

What is the role of folate in the body?

A

Essential for synthesis and repair of DNA including for RBC precursors, amino acid metabolism, neural tube formation in pregnancy, cell division and growth (children and teens growing)

35
Q

What are causes of folate deficiency?

A

Malnutrition
Malabsorption
Pregnancy
Alcohol
Dihydrofolate reductase inhibitors which reduce the levels of biologically active folate:
The antibiotic Trimethoprim (in co-trimoxazole)
The immunosuppressant Methotrexate

36
Q

What are good sources of folate?

A

Leafy greens and legumes

37
Q

What are symptoms of folate deficiency anaemia?

A

Fatigue
Pallor
SOB
Weakness
Angular stomatitis
Glossitis

38
Q

What investigations would be carried out for potential folate deficiency anaemia?

A

FBC
Blood film
To see megaloblasts and hyper-segmented nucleated neutrophils and decreased serum folate

39
Q

What are megaloblasts?

A

Large immature precursors to RBCs found in bone marrow

40
Q

What is macrocytosis?

A

Large RBCs

41
Q

What treatment is given for folate deficiency anaemia?

A

Folate supplements - However, always check B12 levels first. Often also deficient. Then replace B12 first otherwise the B12 will be depleted more due to complex DNA synthesis pathway.

Dietary advice = leafy greens and brown rice

42
Q

Even if not deficient, what should pregnant women be taking in first 12 weeks?

A

400mg prophylactic folate (for neural tube development)

43
Q

What are non-megaloblastic causes of macrocytic anaemia?

A

Alcohol
Hypothyroidism
NALD (Neonatal Adrenoleukodystrophy - rare genetic disorder)
Liver disease

44
Q

What does ‘non-megaloblastic’ mean

A

No hyper-nucleated neutrophils present. These types of anaemias are not primarily associated with impaired DNA synthesis.

45
Q

How does alcohol cause non-megaloblastic anaemia?

A

Toxic to RBCs and depletes folate and B12.

46
Q

How can hypothyroidism cause non-megaloblastic anaemia?

A

Multifactorial - thyroid hormones influence the proliferation and differentiation of red blood cell precursors.

47
Q

How can liver disease cause non-megaloblastic anaemia?

A

The liver is involved with making proteins needed for RBC synthesis. Inflammatory cytokines released can also impact RBC synthesis.

48
Q
A

2a Haematology (16 decks)

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