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Haematology > Macrocytosis and Macrocytic Anaemia > Flashcards

Macrocytosis and Macrocytic Anaemia Flashcards

1
Q

what is the MCV value in macrocytosis?

A

> 100

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2
Q

what is a megaloblast?

A

abnormally large, nucleated red cell precursors

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3
Q

macrocytosis can occur with or without anaemia - true or false?

A

true

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4
Q

megaloblastic anaemias can be characterised into what two things?

A

megablastic

non megaloblastic

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5
Q

how does macrocytosis occur?

A

cells become larger due to defective nuclear maturation and DNA synthesis during haematopoesis

this results in growth without division prior to nucleus extrusion (therefore, large cell size created by failure to become smaller opposed to cells becoming larger)

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6
Q

what is megablastic anaemia?

A

large precursor cells with an immature nucleus leading to macrocytic anaemia

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7
Q

due to their size, macrocytic cells are more prone to what?

A

early breakdown

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8
Q

what are the different causes of macrocytosis?

A

megaloblastic macrocytic anaemia

non megaloblastic macrocytosis

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9
Q

what are the different causes of megaloblastic macrocytic anaemia?

A

B12 and folate deficiency

drugs: cytotoxics

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10
Q

a deficiency in either B12 or folate can impact the functioning of the other - true or false?

A

true

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11
Q

where is B12 mainly sourced from?

A

animal foods

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12
Q

where is B12 absorbed?

A

in the terminal ileum via binding to intrinsic factor

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13
Q

is the body store of B12 small or large?

A

large - lasts 2-4 years

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14
Q

where is folate mainly obtained from?

A

plant foods, especially leafy green vegetables

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15
Q

where is folate absorbed?

A

duodenum

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16
Q

is the body store of folate small or large?

A

much smaller than B12, meaning the body will become deficient in folate before B12

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17
Q

what are dietary causes of B12 deficiency?

A

vegan diet
alcoholism
old age

18
Q

what conditions cause reduced absorption of B12 in the stomach?

A

pernicious anaemia
gastrectomy
PPI
anti histamine

19
Q

what conditions cause reduced absorption of B12 in the small intestine?

A

bacterial overgrowth
coeliac disease (affects terminal ileum)
chrons disease
bowel resection

20
Q

what conditions cause reduced absorption of B12 in the pancreas?

A

chronic pancreatitis

21
Q

what is pernicious anaemia?

A

autoimmune atrophic gastritis in which there is reduction in the production of HCL and intrinsic factor

22
Q

who is pernicious anaemia most commonly seen in?

A

women in their 40s with other autoimmune conditions (thyroid, addisons, vitiligo)

23
Q

what autoantibodies are seen in pernicious anaemia?

A

anti gastric parietal cell = sensitive but not specific

anti intrinsic factor = specific but not sensitive

24
Q

what is the treatment of pernicious anaemia?

A

B12 injections for life

25
Q

what are circumstances which cause low intake of folate?

A

poverty
old age
alcoholism

26
Q

what conditions cause malabsorption of folate leading to folate deficiency?

A

coeliac disease

tropical sprue

27
Q

what conditions cause increased demand of folate leading to folate deficiency?

A 
pregnancy 
malignancy 
myelofibrosis 
exfoliating dermatitis 
haemolytic anaemia
28
Q

what drugs cause folate deficiency?

A

methotrexate
trimethoprim
alcohol
anticonvulsants: phenytoin, valproate

29
Q

as well as the symptoms of anaemia, what else can be seen in megaloblastic macrocytic anaemia?

A

mouth: glossitis / angular stomatitis
jaundice: due to chronic haemolysis
psychiatric: irritability, depression

neurological (more with B12): numbness, tingling, subacute degeneration of spinal cord

weight loss, diarrhoea, infertility

30
Q

what is sub acute combined degeneration of spinal cord and how does it present?

A

insidious degeneration of corticospinal tract and dorsal columns

presentation: parasthesia, ataxia, weakness (sensory symptoms tend to occur first?

31
Q

what is seen on investigation in megaloblastic macrocytic anaemia?

A

serum: low B12/folate

FBC: low Hb, high MCV, reticulocytes

bone marrow biopsy: megalolasts

film: howel jolly bodies, macrovalocytes and hypersegmented neutrophils

32
Q

how is megaloblastic macrocytic anaemia treated?

A

identify and treat underlying cause

folate deficiency = 5mg for 4 months

B12 deficiency = B12 injections (initially on alternative days, then 3 monthly if appropriate)

transfuse red cells only if life threatening

33
Q

why should folate not be given alone in megaloblastic macrocytic anaemia?

A

due to failing to provide B12, precipitating or worsening subacute combined degeneration of cord

34
Q

all the causes of non megaloblastic macrocytosis cause an increase in red cell size by what?

A

altering the red cell membrane

35
Q

what are the main causes of non megaloblastic macrocytosis?

A

alcohol
pregnancy
hypothyroidism
liver disease (target cells on blood film)
marrow failure (myelodysplasia, aplastic anaemia)

36
Q

what is the difference between marrow failure as a cause of non megaloblastic macrocytosis and the other causes eg alcohol?

A

marrow failure will always present with anaemia

37
Q

what is reticulocytosis?

A

increased amounts of circulating reticulocytes due to increased production of RBCs

occurs as marrow response to acute blood loss or red cell breakdown (haemolysis)

38
Q

are reticulocytes bigger or smaller than mature RBCs?

A

bigger

they are analysed along with these for MCV measurement

39
Q

in what conditions is reticulocytosis seen in?

A

haemolysis
haemorrhage
treatment of anaemia
thalassemia (will cause reticulocytosis but not macrocytosis)

40
Q

other than reticulocytosis, what is another kind of spurious (fake) macrocytosis?

A

cold agglutinin disease

Haematology (11 decks)

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