Macrocytic Anaemia Flashcards
Macrocytic anaemias can be split into megaloblastic and non megaloblastic
what does this mean?
Megaloblastic: dna damaged has occured which is causing immature big red blood cells
non megaloblastic: enlargement of rbc without dna damage
Examples of megaloblastic macrocytic anaemia?
B12 deficiency
Folate deficiency
Cytotoxic drugs
Examples of non-megaloblastic macrocytic anaemia?
Alcohol = most common cause of macrocytosis without anaemia
Reticylocytosis, liver disease, hypothyroidism, pregnancy
What does a megaloblastic blood film look like?
Macrocytic anaemias
Megaloblasts
Hypersegmented neutrophils
Leukopenia
What can cause dietery deficiency of vitamin B12?
Vegenism
Malabsorption:
lack of IF causing pernicious anaemia
post gastrectomy
terminal ileum
crohns disease
coeliac disease
tape worms
nitrous oxide abuse
Clinical features of vitamin B12 deficiency anaemia?
Glossitis, angular cheilosis
Depression, psychosis, dementia
Paraesthesia, peripheral neuropathy, absent reflex, SCAD
What is pernicious anaemia?
Autoimmune atrophic gastritis → achlorhydria and lack of gastric intrinsic factor
Most common cause of a macrocytic anaemia in Western countries (Usually >40yrs)
Specific tests: Parietal cell antibodies (90%), Intrinsic factor antibodies (50%), Schilling test
(outdated)
What tests are done to detect pernicious anaemia?
Specific tests: Parietal cell antibodies (90%), Intrinsic factor antibodies (50%), Schilling test
(outdated)
How to treat pernicious anaemia?
Replenish stores with IM hydroxocobalamin (B12) in 6 injections over 2 weeks.
NICE recommend testing for anti-parietal cell / anti-intrinsic factor antibodies as if there is an
autoimmune cause rather than dietary, patients will need 3-monthly IM injections.
Why may folate deficiency occur?
Poor diet
Increased demand: pregnancy or ↑ cell turnover (haemolysis, malignancy, inflammatory disease, and renal dialysis)
Malabsorption: coeliac disease, tropical sprue
Drugs: alcohol, anti-epileptics (phenytoin), methotrexate, trimethoprim
How to treat folate deficiency?
Give oral folic acid. Ensure B12 is checked and replaced prior to folic acid, otherwise
folic acid may exacerbate the neuropathy of B12 deficiency and lead to subacute combined
degeneration of the spinal cord.
A 51-year-old woman presents to her general practitioner complaining of lethargy, pallor and dyspnoea. She has a past medical history of coeliac disease, currently managed with a gluten-free diet and hypothyroidism, managed with levothyroxine.
Which anaemia?
Pernicious
Because autoimmune!
