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Haematology > Macrocytic Anaemia > Flashcards

Macrocytic Anaemia Flashcards

1
Q

What is common MCV cut off for macrocytic anaemia?

A

MCV >100fl

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2
Q

Presentation: tired, tingling in hands & feet.
FBC shows low Hb, low RBC and high MCV.
Which of the following is the most likely explanation for the results?
A. Iron deficiency

B. B12 deficiency

C. Aplastic anaemia

D. Acute myeloid leukaemia

A

B12 deficiency

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3
Q

Presentation: collapsed at home, alcohol excess.
FBC shows only high MCV, everything else normal.
Which of the following is the most likely explanation for the results?
A. Iron deficiency

B. B12 deficiency

C. Life-style

D. Acute myeloid leukaemia

A

Life-style

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4
Q

Presentation: pregnant but low B12, everything else normal. Which of the following is the most likely explanation for the results?
A. Iron deficiency

B. B12 deficiency

C. Pregnancy

D. Folate deficiency

A

Pregnancy

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5
Q

Causes of macrocytosis? (true and false)

A

megaloblastic,

non-megaloblastic

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6
Q

What triggers erthryoblast to stop dividing and lose their nucleus?

A

Critical Hb Content

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7
Q

Megaloblast definition

A

abnormally large nucleated red cell precursor with an immature nucleus

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8
Q

Megaloblastic anaemias characterised by

A

lack of red cells due to issues with DNA synthesis and nuclear maturation in the precursor cells in marrows

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9
Q

In maturing megaloblasts, division is increased/reduced and apoptosis increased/reduces

A

division reduced and apoptosis increases

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10
Q

In megaloblastic anaemia, cytoplasmic development and Hb accumulation are normal. When Hb level reached the nucleus is kicked out and so bigger than normal red cell left - macrocyte. T/F?

A

True

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11
Q

The larger cell size in megaloblastic anaemia is due to the increase in the size of the developing cell. T/F?

A

False - is due to a failure to become smaller

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12
Q

List 5 causes of megaloblastic anaemia

A

pernicious anaemia most common -> B12 deficiency,
folate deficiency,
drugs e.g. PPis/H2-receptor antagonists,
rare inherited abnormalities e.g. cubulin receptor deficiency

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13
Q

Role of B12 and folate in haem system and nervous system?

A

DNA synthesis and nuclear maturation - haem system,

DNA modification and gene activity - nervous system

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14
Q

Causes of B12 deficiency?

A

insufficient dietary intake e.g. vegans, vegetarians,
malabsorption e.g. pernicious anaemia, coeliac disease, surgery so lack of intrinsic factor, PPIs, atrophic gastritis, jejunum: bacterial overgrowth, duodenum: Crohn’s, chronic pancreatitis
HIV

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15
Q

What is macrocytosis?

A

Normal Hb but high MCV so before macrocytic anaemia

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16
Q

Which is more common and more commonly causes megaloblastic anaemia- vitamin B12 or folate deficiency?

A

B12 deficiency

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17
Q

What is pernicious anaemia?

A

autoimmune condition with destruction of gastric parietal cells

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18
Q

What is deficient in pernicious anaemia that causes B12 malabsorption and deficiency?

A

Intrinsic factor

19
Q

What conditions are pernicious anaemia associated with?

A

Atrophic gastritis,

personal/FH of autoimmune disorders e.g. hypothyrdoisim, vitiligo or Addison’s disease

20
Q

Where are folates absorbed?

A

In jejunum & duodenum

21
Q

What are dietary folates converted to?

A

Monoglutamate

22
Q

Causes of folate deficiency?

A

inadequate intake e.g. alcoholics
malabsorption e.g. Coeliac, Crohn’s,
excess utilisation e.g. Haemolysis, exfoliating dermatitis, pregnancy, malignancy,
drugs e.g. anticonvulsants

23
Q

Why are dietary causes of folate deficiency more likely than dietary causes of B12 deficiency?

A

Because folate stores are only 4 months whereas B12 stores are 2-4years

24
Q

Source of B12?

A

Animal

25
Q

Source of folates? (3)

A

liver,
leafy veg,
fortified cereals

26
Q

Where is B12 absorbed?

A

ileum

27
Q

What is daily requirement of B12?

A

1.5ug/day

28
Q

What is daily requirement of folate?

A

200ug/day

29
Q

7 clinical features common to both B12 and folate deficiency?

A 
anaemia signs & symptoms, 
weight loss, 
diarrhoea, 
infertility, 
sore tongue, 
jaundice, 
developmental problems
30
Q

What symptoms are more associated with vit B12 deficiency?

A

neurological problems - posterior/dorsal column abnormalities, neuropathy, dementia or psychiatric manifestations

31
Q

How can B12/folate deficiencies present on lab diagnosis? (6)

A 
macrocytic anaemia, 
pancytopenia in some patients, 
serum B12/folate (not very useful), 
autoantibodies anti GPC or anti IF, 
Schilling's test in past, 
bone marrow exam rarely,
32
Q

What does blood film in B12/folate deficiency show?

A

macrovalocytes and hyperhsegmented neutrophils normally 3-5 nuclear segments)

33
Q

anti gastric parietal cell auto-antibodies are flawed how?

A

are sensitive but not specific

34
Q

anti intrinsic factor antibodies are flawed how?

A

are specific but not sensitive

35
Q

Where is intrinsic factor normally absorbed?

A

terminal ileum

36
Q

B12 and folic acid role?

A

involved in converting folic acid into its active form

37
Q

Megaloblastic anaemia treatment?

A

Vit B12 injections for life in pernicious anaemia,
folic acid orally 5mg,
ONLY if potentially life-threatening transfuse red cells

38
Q

Causes of non-megaloblastic macrocytosis? Which associated with anaemia and which may not be?

A

alchohol - may not be assoc. with anaemia,
liver disease - may not be assoc. with anaemia,
hypothyroidism - may not be assoc. with anaemia,
marrow failure e.g. myelodysplasia, myeloma, aplastic anaemia - associated with anaemia

39
Q

Causes of spurious macrocytosis?

A

reticulocytosis,

cold-agglutinins,

40
Q

What can cause reticulocytosis leading to a spurious macrocytosis?

A

reticulocytosis occurs as a marrow response to acute blood loss or haemolysis

41
Q

Why might patients with pernicious anaemia appear mildly jaundiced?

A

Due to intramedullary haemolysis due to ineffective erythropoiesis. red cells die prematurely in the marrow, haemoglobin and lactate dehydrogenase are released from dead red cells and Hb is converted to bilirubin

42
Q

How can pancytopenia complicate megaloblastic anaemia?

A

Because nuclear maturation defects can affect multiple lineages

43
Q

After macrocytosis confirmed, a blood film should be carried out to investigate cause. If reticulocytes are absent, this suggests what type of cause of macrocytosis?

A

non-megaloblastic e.g. alcoholism, hypothyroidism or liver cause

Haematology (25 decks)

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