Anaemia and microcytic anaemias Flashcards
what is anaemia
reduced total red cell mass
steady state anaemia adult male
Hb <130g/L
Hct <0.38
steady state anaemia adult female
(Hb and Hct)
Hb <120g/L
Hct <0.37
normal Hb male
130-180g/L
normal Hb female
120-160g/L
how can we measure Hb concentration
(4 step process)
- Burst the red cells to create Hb solution
- Stabilise the Hb molecules
- Measure the optical density at 540nm
- then basically measure the redness
the redder it is the more Hb
how do we measure Haematocrit
Ratio (or commonly expressed as the percentage) of the whole blood that is red cells if the sample was left to settle
Modern machines calculate this by adding up the volume of the red cells it counts (if we know the number and size of cells it can work it out)
when are Hb or Hct NOT good markers of anaemia?
- acute trauma
- patient has been given lots of fluids - Hb can be falsely low
are reticulocytes smaller or larger than average red cells?
larger
why do reticulocytes stain purple and not red?
still have some RNA which stains blue
what does the MCV tell us
average size of the red cells
pathophysiological classification of anaemia
decreased production (low reticulocyte count)
increased destruction (high reticulocyte count)
anaemia - decreased production types
- hypoproliferative anaemia
- maturation defect (failure to produce Hb or failure of cell division)
anaemia - increased destruction types
- blood loss
- haemolysis (premature red cell destruction)
in increased destruction anaemia will the reticulocyte count be high or low
high because trying to replace
MCV low - what type of anaemia
microcytic
MCV high - what type of anaemia?
macrocytic
If MCV low (microcytic) consider problems with __________
haemoglobinisation
If MCV high (macrocytic) consider problems with __________
cell division ie maturation
does haemoglobin synthesis occur in the nucleus or the cytoplasm of red cell precursors?
cytoplasm
what do you need to make Hb
Available iron, porphyrin ring, globins (alpha and beta)
microcytic anaemia - what’s going on
missing one of the elements needed to make haemoglobin: Available iron, porphyrin ring, globins (alpha and beta)
nucleus machinery is intact so cells keep dividing
One of the signals to stop dividing is Hb accumulation
This is delayed
As a result more cell divisions occur and the cells are smaller (microcytic)
- too many divisions, progeny get smaller, not as much Hb in them
is microcytic anaemia a problem with the nucleus or cytoplasm?
cytoplasm
commonest cause of microcytic anaemia
iron deficiency
causes of hypochromic microcytic anaemias
haem deficiency
- lack of iron for erythropoiesis
- problems with porphyrin synthesis
globin deficiency
- Thalassaemia (trait, intermedia, major)
iron is potentially toxic, true or false
true - so always chaperoned! always stuck to another protein in the body - transferrin or ferritin
where is the majority of our iron
in our blood cells
how much iron do we lose a day
1mg/day (small amount) just from skin shedding and stuff idk
what is iron bound to in the transport system
transferrin
iron is stored in ______ mainly in the _______
ferritin
liver
what is used to assess storage iron status
serum ferritin
how many binding sites for iron does transferrin have
2
what is transferrin role in transporting iron
Transports iron from donor tissues (macrophages, intestinal cells and hepatocytes) to tissues expressing transferrin receptors (especially erythroid marrow)
what is ferritin
large intracellular protein
can store loadsss of iron
what does low ferritin mean
iron deficiency (because we don’t make lots of ferritin if we don’t have lots of iron to store)
iron deficiency can be confirmed by a combination of _________ (decreased functional iron) and reduced _______ _____ (low serum ferritin)
anaemia
storage iron
Sequential consequences of negative iron balance
- Exhaustion of iron stores (ferritin falls)
- Iron deficient erythropoiesis then starts (MCV starts to fall)
- Anaemia then develops
- Epithelial changes (late effects in other sites of the chronic lack of iron)
-skin
-koilonychia
-angular chelitis
causes of iron deficiency
(3 points)
- insufficient dietary iron (rare)
- losing iron - usually blood loss (GI, menstrual, urinary)
- malabsorption e.g. coeliac
where is iron absorbed
proximal small bowel
causes of chronic blood loss
Menorrhagia
Gastrointestinal
-Tumours
-Ulcers
-Non-steroidal anti-inflammatory agents
Haematuria
A small volume gastrointestinal blood loss can occur without any symptoms or signs of bleeding. 5mls of blood a day would be ____mg iron and might go unnoticed
2.5
oral iron side effects
Mainly GI and related to elemental iron load on the gut
Constipation, nausea, vomiting, abdo pains, dark stools
This can result in poor compliance
oral iron side effects are dose dependent, true or false
true - more you give, more side effects
daily dose of iron that is sufficient for anaemia
65mg
what is sodium feredetate (sytron)
liquid prep of iron, used in paediatrics
when would parenteral (IV) iron be used instead of oral?
Poor tolerance of oral iron
Poor compliance with oral iron
Malabsorption issues (rare)
Specific situations (eg renal anaemia)
when giving iron for anaemia, how long after starting treatment do we assess response?
4-6 weeks (FBC)
iron treatment for anaemia - typically need to continue for how long to replenish?
couple of months when you’re back to normal
Sequential consequences of negative iron balance
- Exhaustion of iron stores (ferritin falls)
- Iron deficient erythropoiesis (MCV falls)
- Microcytic anaemia develops
- Epithelial changes (effects elsewhere) - skin, koilonychia, angular chelitis
