Physiology of Anaemia Flashcards
define anaemia
reduced total red cell mass
Hb concentrations indicating anaemia
- males Hb <130g/L, Hct <0.38
- females Hb <120g/L, Hct <0.37
- pregnancy Hb <110g/L
- 6-14 years= 120g/L
- 6 months- 6 years= 110g/L
how to measure Hb concentration?
spectrophotometric method
what is the spectrophotometric method?
red cells are burst to create a solution and optic density measured as Hb is red
what is Beer’s Law
colour is proportional to concentration
how is Hct measured?
spinning blood in a centrifuge which separates components allowing calculation of percentage/ ratio
when are methods of measuring Hb and Hct not good?
rapid blood loss= need plasma expansion
haemodilution
what is the normal response to anaemia?
reticulocytosis
what are reticulocytes?
red cells that have just left the bone marrow, larger than RBCs and still have RNA so stain purple/deep red
how long does reticulocytosis take?
few days
two causes of anaemia
- decreased production (low reticulocyte count)
2. increased loss/ destruction of red cells (high reticulocyte)
two causes of decreased production of red cells
- hypoproliferative= reduced erythropoiesis
2. maturation abnormality= erythropoiesis ineffective
two types of maturation abnormality
- cytoplasmic defects= impaired globinisation
2. nuclear defects= impaired division
what can be used to distinguish cytoplasmic and nuclear defects?
MCV
cause of low MCV (microcytic)
globinisation problems
high MCV (macrocytic)
division problem
what is a megaloblast?
abnormally large nucleated cell with an immature nucleus
what are megaloblastic anaemias?
lack of red cells due to defects in maturation
how are megaloblastic anaemias formed?
development and Hb accumulation if normal but it fails to become smaller, nucleus is extruded leaving a bigger than normal red cell (macrocyte)
