what is normal and interpreting blood counts Flashcards
what is the difference between a normal range and a reference range?
Normal range: much harder to define, more vaguer concept
Reference: range derived from a carefully defined reference population
what are the units of WBC, RBC and Hb?
WBC - x10^9/L
RBC - x10^12/L
Hb - g/L
what are the units of PCV/Hct, MCV and MCH?
PCV/Hct - ratio
MCV - fl
MCH - pg
what are the units of MCHC and platelets?
MCHC - g/L
Platelets - x10^9/L
what is the MCH?
- ABSOLUTE amount of Hb in an individual RBC
- in micro/macrocytic anaemias, MCH tends to parallel MCV
what is the MCHC?
- CONCENTRATION of Hb in RBC
- will change with shrinkage or growth of cell
- MCH will not change
how do you carry out a WBC, RBC, platelet count>
counted by machines by enumerating electronic impulses generated when cells flow between a light source and a sensor
how do you measure Hb?
- measured in a spectrometer
- convert Hb to a stable form and measuring light absorption
how do you measure PCV or Hct?
measured by centrifuging a blood sample
how do you calculate MCV?
- total number of RBCs in a sample divided by total number of RBCs
- PCV/RBC
- measured using light scattering, interruption in an electric field
how do you calculate MCH?
- amount of Hb in a given volume of blood divided by number of RBCs in same volume
- Hb/RBC
how do you calculate MCHC?
- amount of Hb in volume of blood divided by proportion of sample represented by RBCs
- Hb/PCV
- measured using light accurately
what does a high MCHC indicate?
- irregularly contracted cells
- spheroidal cells
what is polycythaemia?
- too many RBCs in circulation
- inc. Hb, RBC, Hct
what would you find in the physical exam of someone with polycythaemia?
- splenomegaly
- abdo mass
- cyanosis
