Macrocytic anaemia Flashcards
Explain the pathophysiology of megaloblastic anaemia
- results from impaired DNA synthesis, preventing the cells from dividing normally
- Rather than dividing, they grow into large, abnormal cells
Give 2 Megaloblastic causes of macrocytic anaemia
- vitamin B12 deficiency
- folate deficiency (e.g. methotrexate therapy)
Give 5 Normoblastic causes of macrocytic anaemia
- alcohol
- liver disease
- hypothyroidism
- reticulocytosis (from haemolytic anaemia or blood loss)
- myelodysplasia
- drugs: azathioprine
- pregnancy
What is vitamin B12 mainly used for in the body
RBC development
maintenance of the nervous system
Give 4 causes of vitamin B12 deficiency?
- pernicious anaemia (mc)
- post gastrectomy
- vegan diet or a poor diet
- disorders/surgery of terminal ileum - Crohn’s: following ileocaecal resection
- drugs: PPi or metformin
Features of vitamin B12 deficiency
- soretongue and mouth
- neurological symptoms
- mood disturbances
What neurological symptoms does Vitamin B12 deficiency cause
- dorsal column is usually affected first: loss of proprioception and vibration sense
*peripheral neuropathy with distal paraesthesia - visual changes
How is Vitamin B12 managed
No neuro involvement: 1 mg of IM hydroxocobalamin 3x pw for 2 weeks, then once every 3 months
What is pernicious anaemia?
An autoimmune disorder affecting the gastric mucosa, resulting in vitamin B12 deficiency.
What is the pathophysiology of pernicious anaemia?
- parietal cells of the stomach produce intrinsic factor which is essential for the absorption of vitamin B12 in the terminalileum
- in pernicious anaemia, Autoantibodies to intrinsic factor and/or gastric parietal cells impair vitamin B12 absorption.
RFs for pernicious anaemia
- mc in females
- other autoimmune disorders: thyroid,T1DM, Addison’s,vitiligo
- blood group A
Describe the features of pernicious anaemia
- General: Lethargy, pallor, dyspnoea.
- peripheral neuropathy, especially in the legs
- subacute combined degeneration of the spinal cord
- neuropsychiatric: memory loss, confusion,depression,irritability
- mild jaundice + pallor = lemon tinge
How is pernicious anaemia investigated
- FBC: macrocytic anaemia
- Vit B12 and folate levels
- antibodies: anti-IF Ab (highly specific), anti gastric parietal cell Ab (low specificity,not useful)
How is pernicious anaemia managed
- IM vitamin B12 replacement
- more frequent doses for patients with neurological features
What cancer does pernicious anaemia predispose affected patients to
gastric cancer
Give some causes of folic acid deficiency
- phenytoin
- methotrexate
- pregnancy
- alcohol excess
If a paient has both a Vitamin B12 and a folic acid deficiency, which should be treated first and why
treat the B12 deficiency first to avoid precipitating subacute combined degeneration of the cord
