Macrocytic Anaemia Flashcards
What are the causes of Megaloblastic Anaemia?
▪️Folate deficiency
▪️Vitamin B12 deficiency
What is a Megaloblast?
Large cells where the nucleus is immature (undeveloped) in comparison to the cell cytoplasm.
This is due to impaired DNA synthesis.
Where is vitamin B12 absorbed?
The terminal ileum
Where is vitamin B12 stored?
The liver
Where is Intrinsic factor produced?
The parietal cells of the stomach
What is the role of intrinsic factor?
IF is involved in the absorption of vitamin B12
What is pernicious anaemia?
The production of antibodies against the parietal cells of the stomach, preventing the absorption of vitamin B12.
Pernicious anaemia is also associated with achlorhydria, as the parietal cells no longer produce acid.
Characteristics of pernicious anaemia include: yellow skin and a beefy tongue
Where is vitamin B12 found in the diet?
Meat and dairy products.
Vegetarians suffer from B12 deficiency.
What is the main role of vitamin B12?
Vitamin B12 is involved in the synthesis of thymidine and therefore DNA synthesis.
Why is pernicious anaemia treated with oral B12, when the vitamin requires IF for absorption?
99% of cobalamin is absorbed bound to IF.
1% of cobalamin is absorbed passively and unbound.
What is the broad classification of Macrocytic anaemia?
Megaloblastic anaemia and Non-megaloblastic anaemia
What effect does B12 deficiency have on the nervous system?
▪️Weakness
▪️Paraesthesia
▪️Gait abnormalities
List the causes of B12 deficiency
▪️Pernicious anaemia
▪️Malabsorption e.g. Gastrectomy, terminal ileal resection, Crohn’s disease, bacterial overgrowth, tape worm
▪️Vegetarian diet
What foods are rich in folate?
▪️Green vegetables
▪️Yeast
▪️Nuts
▪️liver
Name some drugs that act as folate antagonists, and therefore lead to folate deficiency.
▪️Methotrexate ▪️Sulphonamides ▪️Trimethoprim ▪️Phenytoin ▪️Sodium valproate
Where is folate stored?
The liver
Where is folate absorbed?
The duodenum and ileum
What dose of folic acid is taken during pregnancy?
B) When is folic acid first started and how long is it taken in pregnancy?
400 micrograms
5mg in women with high risk of having a baby with a neural tube defect.
B) Started before conception and until 12 weeks of pregnancy
What do low levels of folic acid do to the levels of homocysteine?
🔽Folic acid causes an ⬆️ in homocysteine levels
What is the role of folate?
Folate, via tetrahydrofolate transfers one carbon compounds to purine rings to form the bases involved in the synthesis of DNA.
What are the causes of NON MEGALOBLASTIC, macrocytic anaemia?
▪️Alcohol ▪️Hypothyroidism ▪️Pregnancy ▪️Liver disease ▪️Reticulocytosis
