Practical 1: Anaemia Investigations Flashcards
What method do we use to determine Haemoglobin?
The Drabkin’s method
Why do we measure haemoglobin
(3)
To indirectly evaluate the oxygen-carrying capacity of the blood
It can aid in detecting and evaluating blood loss
Can aid in diagnosing and treating anaemia
Define aneamia
A lower than normal haemoglobin level
What is the Drabkin’s method also called
The cyanmethaemoglobin method
What is the principle behind the Drabkin’s method of measuring haemoglobin
(3)
Drabkin’s fluid contains potassium cyanide and potassium ferricyanide
Potassium ferricyanide converts haemoglobin to methemoglobin
Potassium cyanide converts methemoglobin to red coloured cyanmethemoglobin
What is haematocrit
(2)
A measurement of the proportion of blood that is made up of red cells
The value is expressed as a fraction of cells in blood
List the red cell indices
(3)
Mean corpuscular volume (MCV)
Mean corpuscular Hb (MCH)
Mean corpuscular Hb concentration (MCHC)
What three values do we require to determine our red cell indices?
Red blood cell count (RCC)
The Haemoglobin
The Haematocrit
What is the mean corpuscular volume
The average volume of a red blood cell expressed in femtolitres
What is the equation for mean corpuscular volume
(Hct% x 10)/ RBC (x10^12/L)
What is the mean corpuscular haemoglobin (MCH)
The average weight of Hb in a red blood cell, expressed in picograms
What is the equation for mean corpuscular haemoglobin?
Hb/ RBC
What is Mean corpuscular haemoglobin concentration
The average concentration of Hb in a given volume of blood. The units are grams per litre
What is the equation for MCHC
Hb x 100/ Hct %
What does MCV indicate
Size of the rbcs
What does the MCH indicate
The colour of the rbcs
What does a low MCV and MCH indicate
Microcytic and hypochromic rbcs
What causes microcytic and hypochromic rbcs
Iron deficiency
Thalassaemia
What does a normal MCV and MCH mean
Normocytic and normochromic rbcs
What diseases will rbcs be normocytic and normochromic?
(4)
Blood loss (acute)
Haemolysis
Chronic disease
Marrow infiltration
What does raised MCV indicate
Macrocytic rbcs
What causes macrocytic rbcs
Megaloblastic anaemias
At what absorbance should your Drabkin’s assay be read
540nm
For how long should you incubate your assay
5 mins at room temperature
How do you carry out a haematocrit
3/4 fill a capillary tube with blood
Seal the end of the tube
Place in centrifuge -> 5mins at 12,000g
Read Hct using reader provided
