Microcytic and Macrocytic Anaemias Flashcards
define anaemia
reduced total red cell mass
what Hb is considered anaemia in males and females?
Hb <130g/l in males
Hb <120g/l in females
which law is used when measuring optical density of red blood cells?
beers law
why is measuring haematocrit not reliable straight away in someone who’s just suffered a massive bleed?
there will be no change- need to wait as plasma to blood volume will be more accurate
what is haemodilution?
lower red blood cell count due to plasma expansion but not actually lost any red cells i.e. giving somone fluids overnight
how can anaemia be classified? (2)
decreased production
increased loss/destruction
what will reticulocyte count be in somone with an anaemia due to
1) decreased production
2) increased loss/destruction
1) low reticulocyte count
2) high reticulocyte count
what is microcytic anaemia?
presence of small red blod cells
what are some causes of microcytic anaemia?
iron deficiency
globin deficiency
problems with prophyrin synthesis (v,v rare)
what are siderocites?
iron accumulating wrong in place in blood cell
(seen in problems w porphyrin ring synthesis)
a problem with Hb production will produce what kind of coloured cells?
hypochromic
how is iron deficiency anaemia confirmed?
anaemia (dec functional iron)
low serum ferritn
what are some causes of iron deficiency anaemia?
relative deficiency- women of child bearing age/ children
absolute deficiency- vegetarian diet
blood loss
Malabsoprtion- coeliac
if menorrhagia is cause of iron deficiency anaemia what is treatment?
ferrosulphate
define macroytic anaemia
red cells have larger than normal volume
how is red blood cell size expressed?
Mean Corpuscular Volume (MCV)
what will HB, RBC and MCV look like in a macrocytic anaemia?
low Hb
low RBC
high MCV
what is the range for red blood cell size?
80-100, >100= macrocytic
what are the two kinds of true macrocytic anaemia?
megaloblastic
non-megalobastic
define megaloblastic anaemia
abnormally large cells with immature nucleus- megaloblasts
where is the defect in megaloblastic anaemia?
defect in DNA synthesis
RNA and Hb sythesis is preserved in megaloblastic anaemia. how does this cause production of macroytes (lrger cells)?
when Hb level in cell is optimal nucleus is extruded leaving behind bigger than normal red cell (macrocyte)
(cytoplasm etc develops normally but nucleus refuses to divide so left with one massive cell that was meant to be two)
why does anaemia occur in megaloblastic anaemia?
even thogh cells are larger there are less as apoptosis occurs to remove defective cells
what are some causes of megaloblastic anaemia?
B12 or Folate deficiency
what is seen in non-megaloblastic anaemia?
red cell membrane changes
what are some causes of non-megaloblastic anaemia?
alcohol
liver disease
hypothyroidism
marrow failure
why is spurious macrocytosis also known as ‘false’?
the volume of mature red cell is normal but the MCV is measured as high
what are some causes of spurious macrocytosis?
inc in reticulocytes in response to acute blood loss/hameolysis
cold-agglutinations, clumps registered as one giant cell
why does an increase in reticulocyte numbers give an increase in MCV?
reticuloytes are slightly larger than fully matured red cells
what are some sources of B12?
meat/eggs
where does B12 absoprtion occur?
distal small bowel
how is B12 modified in order to be absorbed?
binds to R protein in stomach
intrinsic factor released from parietal cells
all travel to duodenum- lower pH
R protien cleaved and B12 binds to intrinsic factor
what are some causes of B12 deficiency?
vegan diet
lack of gastric acid
pH doesn’t change with pancreatic secretion
bacterial overgrowth in small bowel
where is intrinsic factor released?
gastric parietal cells
how does pernicous anaemia cause B12 deficiency?
autoimmune destruction of gastric parietal cell so no longer able to produce intrinsic factor
what should you watch out for in hisotry when dianosing pernicious anaemia?
other autoimmune disorders i.e. hypothyroidism, vitiligo, addisons
how is pernicous anaemia treated?
IM B12 for life
where is folate absorbed?
jejunum
what are some causes of foalte deficiency?
inadequate intake
malabsortion i.e. coeliac, crohns
excess utilisation- haemolysis, pregnancy, malignancy
drugs- anticonvulsant
what are some sources of folate?
liver, leafy veg, fortified cereals
what is the daily requirement of B12 and Folate?
B12- 1.5ug/day
Folate- 200ug/day
what are the clinical features of B12/folate deficiency?
symtptoms of anaemia
wgt loss, diarrhoea
sore tongue, jaundice
developmental problems in children
hypersegmented nuetrophils and macrovalocytes are seen in which kind of anameia?
macrocytic - maegaloblastic anaemia
what auto-antibodies can be checked when investigatign macrocytic anaemia?
anti-intrinsic factor
anti-gastric paretal cell
why can patients with pernicous anaemia present mildly jaundiced?
intramedullary haemolysis causes Hb to be converted to bilirubin causing change in skin colour
neurological problems and psychiatric manifestations are more regularly seen in deficiency of B12 or folate?
B12
if proximal bowel is removed what anaemia will occur?
iron deficiency anaemia
iron deficiency causes which macrocytic/microcytic anaemia?
microcytic
B12 or folate deficiency causes macrocytic/microcytic anaemia?
macrocytic
removal of the distal bowel will cause which anaemia?
macrocytic due to deficiency in B12
