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Haematology > Macrocytosis and Macrocytic anaemia > Flashcards

Macrocytosis and Macrocytic anaemia Flashcards

1
Q

macrocytic anaemia definition

A

anaemia in which the red cells have a larger volume than normal

(so not enough of them, but big)

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2
Q

classification of macrocytosis

A
  • megaloblastic
  • non-megaloblastic
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3
Q

megaloblastic meaning

A

A larger than normal, nucleated red cell precursor (‘mother cell’), with an immature nucleus.

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4
Q

what triggers the normoblast (red cell precursor) to stop dividing and lose nucleus?

A

Hb content

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5
Q

Megaloblastic anaemias are characterised by a lack of ____ cells due to predominant defects in ____ _________ and nuclear maturation in developing precursor cells in the marrow.

A

red
DNA synthesis

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6
Q

megaloblastic anaemias - is the problem the cytoplasm or the nucleus

A

nuclear

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7
Q

what causes megaloblastic anaemia (_______ defects)

A

nuclear defects

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8
Q

causes of megaloblastic anaemia

A

B12 deficiency
Folate deficiency
Others
-Drugs
-Rare inherited abnormalities

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9
Q

why are B12 or folate important?

A

B12 and folate are essential co-factors in linked biochemical reactions regulating:

-DNA synthesis and nuclear maturation - (e.g. blood cell effect)

-DNA modification, gene activity – (e.g. nervous system)

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10
Q

B12/folate is needed to turn uracil to _______

A

thymine

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11
Q

what food does B12 come from

A

meat eggs fish

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12
Q

causes of B12 deficiency - what sort of diet

A

vegan

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13
Q

causes of B12 deficiency -stomach

A
  • PA
  • atrophic gastritis
  • PPIs
  • gastrectomy/bypass
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14
Q

causes of B12 deficiency - small bowel

A

jejunum
- bacterial overgrowth
- coeliac
duodenum
- resection
-crohns

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15
Q

what is pernicious anaemia

A

Autoimmune condition where antibodies target either the gastric parietal cells or intrinsic factor, resulting in a lack of intrinsic factor and a lack of absorption of vitamin B12

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16
Q

what other conditions is pernicious anaemia associated with

A

atrophic gastritis and personal or family history of other autoimmune disorders (eg. hypothyroidism, vitiligo, Addison’s disease)

17
Q

where is folate absorbed

A

Absorbed in jejunum (diffusion and actively)

18
Q

Dietary folates converted to ___________________

A

monoglutamate

19
Q

causes of folate deficiency

A

Inadequate intake
Dietary cause more likely than B12 due to lesser stores (e.g. ‘alcoholic excess’)

Malabsorption
-Coeliac disease, Crohn’s disease

Excess utilisation
-Haemolysis
-Exfoliating dermatitis
-Pregnancy
-Malignancy

Drugs
- anticonvulsants

20
Q

Clinical Features common to both B12 and folate deficiency

A

Symptoms/signs of anaemia
weight loss, diarrhoea, infertility
Sore tongue, jaundice
Developmental problems

21
Q

clinical features more with vit B12 deficiency than folate

A

Neurological problems –dorsal/lateral column abnormalities, neuropathy, dementia, psychiatric manifestations

22
Q

Laboratory diagnosis of B12/folate deficiency

A

Macrocytic anaemia (red cell count is low)

Pancytopenia (all cells low) in some patients

Blood film shows macrovalocytes and ‘hypersegmented’ neutrophils (normally 3-5 nuclear segments)

Assay B12 and folate levels in serum

Check for auto-antibodies
- anti gastric-parietal cell (GPC)
- anti-intrinsic factor (IF)

23
Q

what might blood film show in B12 and folate deficiency

A

macrovalocytes and ‘hypersegmented’ neutrophils (normally 3-5 nuclear segments)

24
Q

lab diagnosis of B12/folate deficiency - autoantibodies - which are sensitive and which are specific

A

anti gastric-parietal cell (GPC) - sensitive, not specific

anti-intrinsic factor (IF) – specific, not sensitive

25
Q

treatment of megaloblastic anaemia

A

treat cause e.g. diet/oral supplementation

Vit B12 injections for life in pernicious anaemia

Folic acid tablets (5mg per day) orally

only if potentially life-threatening - transfuse red cells extremely cautiously

26
Q

causes of non-megaloblastic macrocytosis

A
  • alcohol
  • liver disease
  • hypothyroidism
  • marrow failure
27
Q

which causes of non-megaloblastic macrocytosis may NOT be associated with anaemia

A
  • alcohol
  • liver disease
  • hypothyroidism
28
Q

which causes of non-megaloblastic macrocytosis are associated with anaemia

A

Marrow failure
- Myelodysplasia
- Myeloma
- Aplastic anaemia

29
Q

polychromasia meaning

A

you have more immature red blood cells than what’s considered normal - more colours on stain??

30
Q

spurious (false) causes of macrocytosis

A
  • reticulocytosis (analyser counts these bigger cells)
  • cold-agglutinins (causes clumping so the analyser counts them as one cell)
31
Q

Patients with pernicious anaemia can appear mildly jaundiced due to _________ ___________

A

intramedullary haemolysis

32
Q

what drugs cause folate deficiency

A

anticonvulsants

33
Q

pernicious anaemia treatment

A

Vitamin B12 injections for life

Haematology (36 decks)

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