Anaemia and microcytic anaemias Flashcards
adult males normal HB
<130g/L
adult females normal HB
<120g/L
where does red cell rpoduction take place and how
bone marrow
severe eurythoid precursors cluster around a central nursing histiocyte
how can hb be measured using a spectrophotometric method
burst red cell to create hb solution stabilise Hb molecules - cyanmetHb measure optical density at 540nm OD proportional to concern - beers law Hb concentration calculated against known reference
how to measure haematocrit
ratio of whole blood that is red cells if the sample was left to settle
what is the response to anaemia
increase red cell production - reticulocytosis
what are reituclocytes what do they still have remnants of stain how blood film how long does up regulation take
red cells that have left the bone marrow, larger than av red cells
remnants of protein making machinery
stain purple/deeper red
blood film - polychromatic
up regulation of reticulocyte production by the bone marrow in response to anaemia takes a few days
what can automated analysers say about red cells
physical - size, light scattering properties
rapid and reproducible
what is measured and calculated in analysers
Hb conc
number of red cells
size of red cells - MCV
haemotacrit
mean cell hb
mean cell hb conc
what other things can be looked for
blood film - cell morphology
reticulocyte count - assess marrow response
pathophysiological classification of anaemia
decreased production
- hyperproliferative (low amount of erythro)
- maturation abnormality - erythro present but ineffective — cytoplasmic defects, nuclear defects
increased loss or destruction of red cells
- bleeding
- haemolysis
low MCV
microcytic
problems with haemoglobinisation
MCV high
macrocytic
problems with maturation
where does hb synthesis occur and what do defects result in
cytoplasm
small cells that are hypo chromic (lacking in colour)
what is needed to make hb
globes
haem - porphyrin ring, Fe 2+
shortages leads to small red cells w low Hb content
hypo chromic microcytic anaemias
deficient haemoglobin synthesis : cytoplasmic defect
causes of hypo chromic microcytic anaemias
haem deficiency
- lack of iron for erythropoiesis: iron defic, chronic disease so normal body iron but lack of available iron
- problems with porphyitin synthesis: lead poisoning, pyridoxine responsive anaemias
- congenital sideroblastic anaemia
global defic
-thalassaemia (trait, intermedia, major)
how does iron exist
Fe2+
oxidised - Fe3+
why is iron essential
oxygen transport
electron transport
why does iron need to be handled safely by the body
potentially toxic as generates are radicals
adult hb units
4 global sub units each w a haem molecule
haem group contains a single Fe2+ ion
each group can bind to one o2 molecule
fully saturated 1g of hb
will bind 1.34ml of o2
where is most of the iron in the body
in hb
how much iron is absorbed
a small amount
iron turnover
fast - 4mg in pool and move 20mg/day
what is circulating iron bound to
transferrin
where is circulating iron transferred to
to the bone marrow macrophages that feed it to red cell precursors
where is iron stored
in ferritin mainly in the liver
tests to assess iron status
function iron - hb
transported iron - serum, transferrin, transferrin saturation
storage iron - serum ferrratin
what is transferrin
protein with two binding sites for iron atoms
what does transferrin do
transports iron from donor tissues (macrophages, intestinal cells and hepatocytes) to tissues expressing transferrin receptors (esp erythroid marrow)
what does percentage sat of transferrin with iron measure
when is it reduced/increased
measures iron supply
reduced in iron deficiency, in anaemia of chronic disease
increased in genetic haemachromatosis
what is ferritin
large intracellular protein
spherical protein stores what
up to 4000 ferric ions
tiny amount of ferritin present in serum - reflect intracellular ferritin synthesis in response to iron status in host
serum ferritin measures what
indirect measure of storage iron
low ferritin
iron deficiency
how can iron defic be confirmed
comb of anaemia (low functional iron) and reduced storage iron (low serum iron )
causes of iron defic
not eating sufficient to meet physiological requirements
- relative defic - preg
- absolute defic - vegetarian
losing blood
not absorbing enough - coeliac, achlorhydria
causes of chronic blood loss
menorrhagia - commonest
GI - tumours, ulcers, NSAIDs
haematuria
av menstrual blood loss
av daily intake
iron status
heavy menstrual blood loss
30-40ml/month = 15-20mg/month
daily intake 1mg/daily
status precarious
> 60ml i.e. >30mg/month
sequence of neg iron balance
exhaustion of stores
iron deficient
erythropoiesis - falling red cell MCV
microcytic anaemia
epithelial changes - skin,, koilynychia
occult blood loss
small volume GI blood loss can occur without any symp or signs of bleeding
this can outstrip max dietary iron absorption or iron and result in anaemia
iron supplements