Macrocytic anaemia Flashcards
What is the cause of macrocytic anaemia?
1) Vitamin B12 (pernicious anaemia)
2) folate deficiency.
3) Alcohol
4) liver disease
5) hypothyroid
6) pregnancy
Vit B12 and folate is needed for DNA synthesis. Deficiency —-> less cell division)
What are the sources of Vitamin B12?
Vitamin B12 can be obtained from animal sources e.g. meat, eggs, fish, milk
Who is at risk of Vitmain B12 deficiency?
1) Low dietary intake - vegans
2) Impaired absortption (pernicious anaemia)
3) abnormal utilisation (congenital transcobalamin II deficiency)
What are the causes of impaired Vitamin B12 absorption from the stomach?
1) Pernicious anaemia
2) Gastrectomy
3) Congenital deficiency of intrinsic factor
What are the causes of impaired vit B12 absorption from the small bowel?
1) illeal disease / resection
2) bacterial overgrowth
3) tapeworm
What is pernicious anaemia and how does it lead to macrocytic anaemia?
Pernicious anaemia is an autoimmune disorder causing destruction of the parietal cells in the stomach.
Parietal cells secrete intrinsic factor which is needed for the absorption of Vit B12.
Pernicious anaemia —>less parietal cells —> less intrinsic factor —> less absorption of Vit B12.
Apart from macrocytic anaemia, what are the other side effects of low Vit B12?
- peripheral neuropathy
- dementia
- weakness and ataxia
What foods contain folate?
- green leafy vegetables
- liver / kidney meat
What is the main causes of poor intake of folate?
Excess alcohol
What are the causes of poor folate intake?
GI diseases such as crohn’s, coeliac disease and gastrectomy can lead to poor intake.
Give examples of “anti-folate” drugs?
1) Anticonvulsants e.g. phenytoin, primidone
2) Methytrexate
3) Pyrimethamine
4) Trimethoprim
What physiological states would lead to excess utilization of folate?
- pregnancy
- lactation
What pathological states would lead to excess folate utilization?
- haematological disease with increased RBC production e.g. (haemolytic anaemia such as sickle cell, thalasaemia)
- malignant disease —> increased cell turnover
- Inflammatory diseases
- dialysis
Where is folate and vit b12 absorbed?
Iron = duodenum
Folate = jejunum
Vit B12 = ileum
What invx are done for macrocytic anaemia?
1) FBC (low hb, high MCV)
2) blood film (macrocytes with hypersegmented polymorphs with multilobular nucleus)
3) Bone marrow (large cells, large immature nuclei, finely dispersed chromatin)
4) Serum bilirubin (raised due to in effective erythropoesis and premature break down of RBC)
5) Serum methylmalonic accid (MMA) and hommocysteine (HC) : MMA raised in B12 def HC raised in Folated def.
6) Serum folate
7) Serum Vit B12
