Anaemia Intro/ Microcytic Anaemia Flashcards
what is anaemia
reduced total red cell mass
haemoglobin concentration is a surrogate as is haematocrit
what Hb levels mean anaemia in males and females
adults males Hb <130
adult females Hb <120
what is metHb
haemoglobin with Fe3+ instead of Fe2+ (oxidised)
how do you measure haematocrit
as a ratio of the whole blood the is redd cells if the sample was left to settle
it is a percentage eg. 50% or 0.5
not commonly used now
when are Hb/hct not good markers of anaemia
someone with rapid large blood loss (because blood is lost but it hasn’t yet been diluted by plasma to make up the volume)
haemodilution - giving someone fluid overnight to increase their plasma volume causing an anaemia
how does the body respond to anaemia
making more red cells
- reticulocytosis - making reticulocytes
what are reticulocytes
red cells that have just left the bone marrow- larger than average red cells
still have remnants of protein making so stain purple/deeper red
takes a few days in response to anaemia
what can we measure
Hb concentration
Number of red cells
Size of red cells
what can we calculate
haematocrit
mean cell Hb
mean cell Hb concentration
what other investigations can be done (RBCs)
blood film (look at cellular morphology)
reticulocyte count (assesses marrow response)
additional tests depending on findings
what are the pathophysiological classifications of anaemia
Decreased production (low reticulocyte count)
increased loss or destruction of read cells (high reticulocyte count)
causes of decreased production anaemia
hypoproliferative
-reduced erythropoiesis
maturation abnormality
- erythropoeisis present but ineffective
- can be cytoplasmic defects (impaired haemoglobinisation)
- can be nuclear (impaired cell division)
causes of increased loss/destruction anaemia
bleeding
haemolysis
classifications of anaemia based on morphology
Microcytic
- MCV is low
- consider problems with haemoglobinisation
Macrocytic
- MCV is high
- consider problems with maturation
where doesn’t haemoglobin synthesis occur
cytoplasm
consequences of defects in haemoglobin synthesis
microcytic hypochromic anaemia
small cells without colour due to no haem
causes of microcytic hypochromic anaemia
iron deficiency
problems with porphyrin synthesis - v rare
lead poisoning - rare
anaemia of chronic disease -rare
Globing deficiency
-thalassaemia
what is iron essential for
oxygen transport
-Hb, myoglobin
Electron transport
-mitochondrial production of ATP
how much iron is absorbed per day (without treatment)
1mg/day
how much iron is circulating in the plasma and how much in marrow
4mg
150mg in marrow
what is iron stored in
ferritin
macrophage stores and liver stores
however most of iron at one time is in Hb
what tests can be done to check iron status
functional iron - Hb
transported iron - serum iron, transferrin, transferrin saturation
storage iron - serum ferritin
what is transferrin
protein which binds two iron molecules
transports from donor tissues (macrophages, hepatocytes, intestinal cells) to tissues expressing transferrin receptors (eg. erythroid marrow)
transferrin saturation reflects iron supply
- reduced in iron deficiency
- reduced in anaemia of chronic disease
- increased in genetic haemachromotosis
what is ferritin
large intracellular protein
spherical protein which stores up to 4000 ferric ions
tiny amount of ferritin present in serum which reflects intracellular ferritin synthesis in response to iron status
serum is an easy measurement of storage iron
low ferritin ALWAYS means iron deficiency
produced only if there is iron to store
how do you confirm iron deficiency anaemia diagnosis
decreased functional iron and reduced iron storage (serum ferritin)
causes of iron deficiency
not eating enough iron:
relative deficiency
-women of child bearing age and children
absolute deficiency
-vegetarian diets
v unlikely in men
Losing too much iron (blood loss)
not absorbing enough iron (coeliac disease, achlorhydria)
causes of chronic blood loss causing iron deficient anaemia
Menorrhagia
GI
-tumours, ulcers, NSAIDs
Haematuria
what is normal menstrual blood loss
30-40ml/month
equivalent to 15-20mg/month of iron
heavy menstrual loss >60ml is >30mg of iron a month of iron lost
consequences of iron deficient anaemia
- exhaustion of iron stores
-iron deficient erythropoiesis
-microcytic anaemia
-epithelial changes
(skin, koilonychia)
treatment for iron deficiency anaemia
iron replacement therapy to relieve symptoms
investigations to work out underlying cause
early GI surgery can be curative
