Lecture 1 - The Full Blood Count

Question 1

Full Blood Count Test

Answer 1

It is a haematological ‘profile’ or ‘suite’ of assays
Typically assess:
- RBC
- WBC
- platelets
Mostly measured using automated haematology analyser
Analyte selection varies between analyser and laboratory

Question 2

Directly and Calculated Measurements of RBC Values

Answer 2

Directly
- determined by measurement method
- RBC, Hb
Calculated
- calculated from other measured components
- HCT, MCV, MCH, MCHC, RDW
- may be affected by changes in components e.g. MCHC

Question 3

Hb Measurement

Answer 3

Colourmetric measurement of total hemoglobin
Colourmetric analysis is a method of determining the concentration of a chemical compound in a solution with the aid of a color reagent
Units: g/L

Question 4

RBC Measurement

Answer 4

Count cells
Can be done manually with a haemocytometer or automated by flow cytometry
Units: x10^12/L

Question 5

HCT Measurement

Answer 5

HCT stands for Haematocrit 
A.k.a PCV or packed cell volume
Overall assessment of RBC 'mass'
Represent proportion of whole blood made up of RBC
= MCV x RCC
Units: L/L

Question 6

MCV Measurement

Answer 6

Mean corpuscular volume
The average volume of RBC
= PCV/RCC
Units: femtolitres (fL) = 10^-15

Question 7

MCH Measurement

Answer 7

Mean corpuscular haemoglobin
Average weight of haemoglobin in RBC
= Hb/RCC
Units: pg = 10^-12

Question 8

MCHC Measurement

Answer 8

Mean corpuscular haemoglobin concentration
Average concentration of haemoglobin in RBC
= Hb/PCV
Units: g/L

Question 9

RDW Measurement

Answer 9

Red cell distribution width
Indication of variation in size of RBC
Represents range between smallest and largest RBC
Expressed as a coefficient of variation (%)

Question 10

What happens when blood samples deteriorate over time?

Answer 10

RBCs swell
Platelets aggregate
WBCs break down