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Haematology > Macrocytic Anaemia > Flashcards

Macrocytic Anaemia Flashcards

1
Q

What is macrocytosis?

A

An increase in cell volume (MCV)

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2
Q

What is macrocytic anaemia

A

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

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3
Q

What is mean corpuscular volume measured in

A

femtolitres (1 = 10 to the -15)

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4
Q

What is a normal MCV

A

80-100fl

more than 100 = macrocytic

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5
Q

What does megaloblastic mean?

A

An abnormally large nucleated re cell precursor with an immature nucleus

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6
Q

What are the predominant defects in megaloblastic anaemia

A

DNA synthesis and nuclear maturation

RNA and Hb synthesis is preserved

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7
Q

What is the mechanism that leads to the formation of megaloblastic cells?

A

While the cytoplasm has developed appropriately and is mature enough to divide (it is large) the nucleus is still immature so after enucleation you end up with larger than normal cells.

IMPORTANT- the larger cell size is not due to an uncrea in the size of the developing cell but a failure to become smaller

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8
Q

What are the causes of megaloblastic anaemia

A

B12
Folate
Others - drugs, rare inherited abnormalities

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9
Q

Why does B12 or folate deficiency cause megaloblastic anaemiea

A

B12 and folate are both essential co factors for nuclear maturation.
They enable chemical reaction that provide enough nucleosides for dNA synthesis.

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10
Q

What two biochemical cycles are B12 and folate involved in

A

methionine and folate cycle- these are interlinked cycles

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11
Q

How do the methionine and folate cycles interine

A

Methionin cycle produces s-adenosyl methionine, a methyl donor to DNA and folate intermediates.

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12
Q

What is the folate cycle important for

A

nucleoside synthesis

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13
Q

What are the various causes of B12 deficiency

A 
Dietary deficiency 
Atrophic gastritis
PPIs
Gastrectomy/bypass
Chronic pancreatitis
Bacterial overgrowith
Coeliac
Bowel resection
Crohn's
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14
Q

Where is folate absorbed in the gut

A

the jejunum and duodenum

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15
Q

How long can your body rely on your B12 stores vs folate stored

A

2-4 yrs for B12
4 mths for folate

Become deficient in folate much quicker

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16
Q

Where is B12 absorbed

A

Ileum

17
Q

What is your daily requirement of B12 vs folate

A

B12 much less - 1-3ug/day

Folate - 100ug per day

18
Q

What are the causes of folate deficiecy

A

Inadequate dietary intake- more likely than B12
Malabsoption - coeliac, crohns
Excess utilisation- haemolysis, exfoliating dermatitis, pregnancy, malignancy
Drugs- anticonvulsants, methotrexate

19
Q

What are the symptoms of B12 and/or folate deficiency

A

Symptoms of anaemia
Weight loss, diarrhoea, infertility
Glossitis, jaundice
developmental problems

20
Q

What symptom/sign is specific to B12 deficiency

A

neurological problems- neuropathy, dementia, psychiatric

21
Q

What is pernicious anaemia

A

Autoimmune condition resulting in destruction of gastric parietal cells

22
Q

What is associated with pernicious anaemia

A

FHx of autoimmune conditions

Atrophic gastritis

23
Q

What are the features of the cells in pernicious anaemia

A

Macrocytic
can be pancytopenia
Macrovalocytes and hypersegmented neutrophils on blood film

24
Q

what test can be done to diagnose macrocytic megaloblastic anaemias

A

serum B12 and folate levels- not perfect!
Auto- antibodies= anti intrinsic factors and anti gastric parietal cells
Schillings test - not used anymore
Bone marrow examination - not usually required

25
Q

What are the disadvantages to antibody testing

A

Anti GPC = sensitive, not specific

Anti- IF= more specific, not sensitive

26
Q

How is pernicious anaemia treated

A

B12 injections for life

Folic acid 5mg per day also lifelong

27
Q

What are the causes of non megaloblastic anaemia

A

Alcohol, Liver disease, Hypothyroid –> may not have anaemia

Marrow failure e.g. Myelodysplasia, myeloma, aplastic anaemia —) associated with anaemia

28
Q

What is the problem in anaemia due to alcohol, liver disease and hypothyroid

A

Due to red cell membrane changes

29
Q

What are the causes of spurious macrocytosis

A

reticulocytosis

Cold agglutinin disease

30
Q

What is reticulocytosis and what is it caused by

A

increased no of reticulocytes (which are bigger than mature red cells hence macrocytosis)
Caused by acute bleed or haemolysis

31
Q

what is cold agglutinin disease

A

Cold agglutinin disease is an autoimmune disease characterized by the presence of high concentrations of circulating antibodies, usually IgM, directed against red blood cells.

32
Q

Why does the analyser register cold agglutinin disease as macrocytic

A

the agglutinated red cells clump together and appear as one large cell

33
Q

What important symptom my patients with pernicious anaemia have

A

Jaundice

34
Q

Why do patients with pernicious anaemia get jaundice

A

Red cells die in marrow –> Hb and LDH are released –> Hb converted to bilirubin

Haematology (21 decks)

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