macrocytic anaemia Flashcards
define macrocytic anaemia
Anaemia characterised by larger than normal red blood cells.
Usually deficient in B12 or folate.
pathophysiology of macrocytic anaemia
RBCs are too big and are either
megaloblastic or non-megaloblastic.
what are megaloblasts
large nucleated red blood cells
with hyper-segmented neutrophils with 6 or more lobes
what are megaloblasts associated with
slow/impaired DNA synthesis.
what are the 2 main megaloblastic macrocytic anaemias
- B12 deficiency (years to develop)
- Folate deficiency (months to develop).
what is non megaloblastic anaemia a result of
is usually a result of various factors such as
- alcohol
- liver diseases
- hypothyroidism
what is folate
the natural form of vitamin B9
is folate stored
no
which is why 0.1-0.2mg is needed
daily.
6 causes of folate deficiency
- malnutrition
- malabsorption
- pregnancy
- alcohol
- bacterial overgrowth
- drugs - (trimethoprim or methotrexate).
how is vitamin b12 absorbed
- Vitamin B12 binds to
transcobalamin 1 in saliva - and then binds to intrinsic factor in
the duodenum. - Intrinsic factor is secreted by
parietal cells, forms a B12-IF
complex - and is absorbed in the terminal ileum
what is disrupted in vitamin b12 deficiency
the absorption of vitamin b12
2 main causes of vitamin b12 deficincy
- not having enough b12
- poor absorption
what factors contribute to not having enough vitamin b12
veganism and malnutrition
what factors contribute to having poor absorption of vitamin b12
- gastrectomy
- bowel pathology
- oral contraceptives
- nitrous oxide use
what is pernicious anaemia
Antibodies target either parietal
cells or intrinsic factor,
resulting in decreased B12-IF
complexes.
signs and symptoms of b12 deficiency
*Angular stomatitis
* Glossitis
* yellow skin
* Fatigue
* weakness
neurological symptoms associated with b12 deficincy
- Paraesthesia
- Demyelination
- Muscle weakness
- Altered mental state
signs and symptoms of folate deficiency
- Angular stomatitis
- Fatigue
- Weakness
- shortness of breath
treatment for b12 deficiency
Dietary Advice and B12 supplements.
treatment for folate deficiency
Dietary Advice.
Check B12 and folate levels.
Then give supplements as required. (Folate can decrease B12)
treatment for non-megaloblastic anaemia
treat underlying cause
main investigation for macrocytic anaemia (general)
FBC + Blood film = Macrocytic, high MCV
what does investigation for b12 deficiency show
- Megaloblasts present
- low serum B12
- Anti parietal and anti IF antibodies
what does investigation for folate deficiency show
- Megaloblasts
- low serum folate
- could have low B12
