macocytic & haemolytic anaemia Flashcards
what is another name for vitamin B12
cobalamin
what is the role of vitamin B12
synthesises myelin in the NS and assists in DNA synthesis so involved in cell metabolism
what can prolonged B12 deficiency cause?
severe and irreversible nervous system damage
what type of anaemia does B12 deficiency cause?
macrocytic
how does methionine synthase use B12?
generates tertahydrofolate (THF) and methionine, THF is important in DNA synthesis
What effects does dietary folate help to reduce?
reduced DNA synthetic effects with dietary folate but not reduced myelin synthesis
what are the main differences between vitamin B12 and folate B9?
B12 - water soluble, in meat eggs cheese animal protein, not destroyed by cooking, absorbed in ileum when bound to IF, stored for 3 years
folate - water soluble, in liver greens yeast, destroyed by cooking, absorbed in duodenum and jejunum, stored for 4 months
how much B12 and B9 do you require?
1 microgram per day of B12 and 150 micro grams per day of B9
how do anaemic symptoms and signs arise from a defieincy in folate or B12?
impaired DNA synthesis, cells don’t divide, overlarge red cells, increased destruction rate, get symptoms
how is B12 absorbed?
bound to protein in foods and released by stomach acid, absorbed by ileum after binding to IF which is produced by parietal cells
what is pernicious anaemia?
B12 deficiency caused by absence or reduction of IF
what does a blood count look like for B12 and folate deficiency?
low Hb
high MCV
low WVC and platelets
what does a blood film look like for B12 and folate deficiency?
oval macrocytes and hypersegmented neutrophils
what is the biochemistry for B12 and folate deficiency?
high LDH
high bilirubin
what are the main causes for B12 deficiency?
nutritional - poor diet/vegan
malabsorption - gastric if pernicious anaemia or surgical gastrectomy, intestinal if crohns
what is perinicious anaemia?
autoimmune more females arian characteristics blood group A due to autoanitbody against parietal cells and IF gastric atrophy, low IF, low acid
what are the clinical features of perinicous anaemia?
insidious (gradual onset but then fatal) anaemia glossitis (tongue inflamed) mild jaundice neurological symptoms (dementia, optic atrophy)
what is the treatment for pernicious anaemia?
intramuscular B12 every 3 months for life
what foods contain folic acid?
meat, vegetables, grains, nuts
what are the causes of folate deficiency?
nutritional - old age, poverty, alcoholism
malabsorption - crohns, coeliac
excess utilisation - pregnancy, lactation, psoriasis
what are the clinical features of folic acid?
same as pernicious anaemia but no neurological symptoms
what is the treatment for folic acid deficiency?
oral folic acid
what is haemolytic anaemia?
due to abnormal breakdown of RBCs - hawmolysis, shortened RBC survival
how does haemolytic anaemia present?
pallor and signs of anaemia
jaundice
gallstones
splenomegaly
