Pernicious anaemia (zero to finals) Flashcards
Vitamin B12 deficiency causes microcytic anaemia. True/false?
False
Macrocytic anaemia
What are the key causes of low vitamin B12?
The key causes of a low B12 are:
- Pernicious anaemia
- Insufficient dietary B12 (particularly a vegan diet, as B12 is mostly found in animal products)
- Medications that reduce B12 absorption (e.g., proton pump inhibitors and metformin)
What is pernicious anaemia?
An autoimmune condition involving antibodies against the parietal cells or intrinsic factor.
What is intrinsic factor?
A glycoprotein produced by the gastric parietal cells.
Intrinsic factor is essential for the absorption of vitamin B12 in the distal ileum.
In pernicious anaemia, autoantibodies target either the parietal cells or intrinsic factor, resulting in a lack of intrinsic factor and a lack of absorption of vitamin B12.
What neurological symptoms can occur with vitamin B12 deficiency?
Peripheral neuropathy, with numbness or paraesthesia (pins and needles)
Loss of vibration sense
Loss of proprioception
Visual changes
Mood and cognitive changes
In patients with peripheral neuropathy, what is important to test for?
Test for vitamin B12 deficiency and pernicious anaemia in patients, particularly in those with pins and needles.
What autoantibodies are used to diagnose pernicious anaemia?
Intrinsic factor antibodies (the first-line investigation)
Gastric parietal cell antibodies (less helpful)
What medication is usually given to all patients with vitamin B12 deficiency?
Intramuscular hydroxocobalamin is initially given to all patients with B12 deficiency, depending on symptoms:
No neurological symptoms – 3 times weekly for two weeks
Neurological symptoms – alternate days until there is no further improvement in symptoms
In those with vitamin B12 deficiency, how are levels often maintained?
Pernicious anaemia – 2-3 monthly injections for life
Diet-related – oral cyanocobalamin or twice-yearly injections
If there is B12 and folate deficiency, which should be treated first?
Essential to treat the B12 deficiency first before correcting the folate deficiency.
Giving patients folic acid when they have a B12 deficiency can lead to subacute combined degeneration of the cord, with demyelination in the spinal cord and severe neurological problems.
What are some of the clinical features of subacute combined degeneration of the cord?
Sensory deficits, paresthesia, weakness, ataxia, and gait disturbance.
What can subacute degeneration of the cord be caused or precipitated by?
B12 deficiency anaemia
