Vitamin B12 and/or folate deficiency Flashcards
What is the function of vitamin B12 and folate in the body?
they are required for synthesis of purine and pyrimidine bases
Describe the relationship between B12 and folate:
vitamin B12 is essential for cell folate generation
Where is B12 absorbed?
Terminal ileum
What molecule aids the absorption of B12 in the terminal ileum?
intrinsic factor
What cells produce intrinsic factor?
gastric parietal cells
Where is folate absorbed?
jejunum
What are the two main causes of folate deficiency?
- Poor diet
- Malabsorption
Give 3 instances where folate consumption is increased:
1) pregnancy
2) haemolysis
3) inflammatory disorders
Give 5 causes of B12 deficiency:
1) pernicious anaemia
2) insufficient dietary intake
3) medications
4) gastrectomy (less intrinsic factor produced)
5) terminal ileum resection (cannot absorb B12)
What type of anaemia does B12 deficiency cause?
Macrocytic (specifically megaloblastic)
What is pernicious anaemia?
an autoimmune condition involving antibodies against parietal cells or intrinsic factor which results in malabsorption of B12
Give 5 neurological symptoms caused by B12 deficiency?
1) peripheral neuropathy with numbness and paraesthesia
2) loss of vibration sense
3) loss of proprioception
4) visual changes
5) mood and cognitive changes
What simple blood test should be conducted for any patient with peripheral neuropathy?
B12 serum levels
Give 6 non-neurological manifestations of B12 deficiency:
- Megaloblastic anaemia
- Mild jaundice
- Anorexia
- Glossitis
- Angular stomatitis
- Pancytopenia (Pancytopenia is a condition in which a person’s body has too few red blood cells, white blood cells, and platelets)
Why is mild jaundice seen in B12 deficiency?
haemolysis of megaloblastic red blood cells increases serum bilirubin
Give 5 blood tests used to diagnose vitamin B12 deficiency:
1) FBC
2) blood film (increased MCV and decreased reticulocytes)
3) B12 and folate serum levels
4) antibodies against IF or parietal cells
5) bilirubin and lactate dehydrogenase levels (indicates haemolysis of megaloblastic RBCs)
What injection is given to those with B12 deficiency?
hydroxycobalamin
How often is IM hydroxycobalamin initially given to patients with B12 deficiency and neurological symptoms?
every other day
How often is IM hydroxycobalamin initially given to patients with B12 deficiency and no neurological symptoms?
3 times weekly for 2 weeks
How often is IM hydroxycobalamin given to maintain B12 levels in those with pernicious anaemia?
2-3 monthly injections
What are the two treatments used to maintain B12 levels in those with dietary-associated B12 deficiency?
1) oral cyanocobalamin
2) twice years IM hydroxycobalamin
Why should B12 deficiency be treated before folate deficiency in patients suffering with both?
giving folic acid in the presence of a B12 deficiency can lead to subacute combined degeneration of the cord
What is subacute combined degeneration of the cord (SACDC)?
demyelination of the spinal cord, causing severe neurological issues such as distal weakness and dementia
A deficiency of which carrier protein leads to B12 not being able to be functionally used in the body causing megaloblastic anaemia?
transcobalamin (a B12 carrier protein required for its functional use)
