anaemia Flashcards
anaemia?
reduced total red cell mass
assuming steady state normal ranges are:
adult males Hb
what is haematocrit?
ratio of the whole blood that is red blood cells if it were left to settle
ie haematocrit of 0.5 means that half of the whole blood is made up of red blood cells
in some situations, hb/haematocrit is not a good marker of anaemia
after a rapid bleed, blood volume could be the same, but plasma expansion has occurred to make up the lost volue i.e. haematocrit would be reduced
also IV fluids results in an increased plasma volume
response to anaemia?
increase red cell production, peripheral blood reticulocytosis
probapo - o - reticulocyte mature RBC
pronormoblast, basophilic normoblast, polychromatophilic/intermediate normoblast, orthochromatic/late normoblast. retic, RBC
reticulocytes
red cells that have just left the bone marrow, larger than average rbcs, have remnants of RNA, stain purple/deep red as a consequence. blood film appears polychromatic
up regulation of reticulocytes by the bone marrow in response to anaemia may take?
a few days
what does polychromasia result from?
residual rna in the cell which gives the classic blue/grey appearance with classic stains
if mcv is low, consider problems with?
haemoglobinisation
if mcv is high, consider problems with maturation
haemoglobin synthesis occurs in the cytoplasm. defects result in small cells
shortage in globins, haem (porphyrin ring or iron) results in ?
small cels with a low hb content
they are small and lacking in colour
y
hypochromic, michrocytic anaeia =
defective haeomglobin synthesis:cytoplasmic defect
causes of microcytic anaemia?
iron deficiency, thalassaemia (globin defiency). some cases of anaemia from chronic disease
iron can exist in what states?
fe2 plus or fe 3 plus
in chronic disease, there is enough iron but not enough available iron
y
why is iron potentially toxic?
it generates free radicals
iron is also essential for electro transport (mitochondrial production of ATP)
u
when fully saturated, 1g of Hb will bind ______ml 02?
1.34
how much iron is absorbed into body each day?
1mg
circulating iron is bound to transferrin, it is transferred to the bone marrow macrophages that feed it to red cell precursors
iron is stored in ferritin mainly in the liver
how many binding sites does transferrin have for iron?
2
transports iron from donor tissues (macrophages, intestinal cells and hepatocytes) to tissues expressing transferring receptors
y
what does percentage saturation of transferrin with iron measure?
iron supply
large intracellular protein, store up to 4000 ferric ions
ferritin
ferritin in serum?
tiny amount
serum ferritin?
reflects intracellular ferritin synthesis in response to the iron status of the host
serum ferritin is an easily measured indirect measure of ?
storage iron
iron deficiency can be confirmed by a combination of a microcytic, hypo chromic anaemia (decreased functional iron) and reduced storage iron (low serum ferritin)
y
causes of iron deficiency?
diet, RELATIVE DEFICIECNY, ABSOLUTE deficiency, bleeding (usually GI), not absorbing enough…relatively uncommon - malabsorption (coeliac and achlorhydria)
what is a relative deficiency?
ir pregnant woman
absolute?
vegetarian diet
causes of chronic blood loss leading to low iron?
monorrhagia, GI (TUMOURS, ULCERS, nsaids)
haematuria
sequential consequences of negative iron balance?
exhaustion of iron stories, iron deficient erythropoiesis (falling MCV), anaemia, epithelial changes (skin, koilonychia)
remember a small volume of GI blood loss can occur without any symptoms or signs of bleeding
this can outstrip the maximum dietary iron absorption of iron and result in anaemia
how can iron absorption be increased?
iron supplements
iron deficiency anaemia requires?
investigation for an underlying cause
anaemia with high reticulocyte count?
bleeding or haemolysis
