Automated haematology Flashcards
White blood count
x109/1
Red cell count
x1012/1
Platelet count
x109/1
Haematocrit
Ratio
Haemoglobin
g/1
Mean cell volume
Fl
Mean cell haemoglobin
Pg
Mean cell haemoglobin concentration
g/1
White cell differential
Absolute count or percentage
Haemoglobin
The iron-containing oxygen transport protein contained within the red cells
Mean cell volume
PCV x10/RBC
Mean cell haemoglobin
HGB x 10/RBC
Mean cell haemoglobin concentration
HGB x 100/ PCV%
MCV
Average size of the erythrocytes (fl)
MCH
Average weight of haemoglobin per cell (pg)
MCHC
Average haemoglobin concentration per cell (g/dl)
Automation
Improve quality attributes of a process
Impedance principle
Red cells are non-conductive, blood is diluted in diluting medium (conductor) ) passed through a charged aperture = count particles that pass through
Current interruption as cell passes through the aperture
1 pulse = 1 cell
Problems, backflow, angle, more than one cell passing through
Solution= hydrodynamic focussing
PLTS are smaller than WBC + RBC
WBC _ second dilution + counting chamber after losing red cells
Automated PCV & MCV
MCV = PCV /RBC
Anomalies
Red cell distribution width
hemoglobin measurement
Losing RBC’s = haemoglobin (Hb/HGB). Convert to cyanmethaemoglobin (oxidation of Fe2 Fe3) reactive compound attaches to Fe³ to form a
stable measurable compound. 540nm
How to separate the subclasses of WBC
Size
nuclear properties
staining properties
Methodologies of counting / measurement
Impedance
Conductivity
Laser scatter
Absorbance cytochemistry
Automated white cell counting example
Principle. Fluorescence: RNA and DNA
Side scatter: internal cell structure
Forward scatter: cell size
How does sysmex count
Each cell passed through the beam scatters light
Fluorescent dyes from preparation stage are excited = emit light at lower frequency
Detectors analyse fluctuations in the brightness
Forward scatter
Info about cell size
Size scatter
Internal cell complexity
Shape & size of nucleus
Number & type of granules
Certain membrane properties
Side fluorescence
Reflects amount of RNA and DNA in the cell (reflects activity)
Cell membrane of white cells to be permeable to fluorescent dye are?
Lysed
Lymphocytes have…
Low complexity, small size, low rna/dna activity unless activated
Monocytes
Larger, more granules on cytoplasm, larger nucleus + nuclei acid content
Neutrophils basophils eosinophils
Larger, most granularity, eosinophils most granularity/neutrophils. Baso sometimes act as neutro
Immature granulocytes can be counted using a
Parameter- find sepsis
Immature myeloid leucocytes found in marrow include.
Band cells
Myelocytes
Metamyelocytes
Promyelocytes
Blast cells
Adaptive flagging algorithm based on shape recognition examines
Number of ‘events’, shape, position, angle, size length and width
Nucleated red cells usually confused with lymphocytes
Nucleated are shrunk instead of lysed due to cell membranes are perforated instead.
Then stained + measured by flow cytometry, forward scatter, side fluorescence.
How to count basophils
Lyce red cells= leaves nucleated forms as bare nuclei.
Use a Diluent of specific pH to shrink cytoplasm of leucocytes apart from basophils.= selective suppression of degranulation of the basophils = allows separation into basophils, nucleated red cells + other leucocytes
Nucleated red cell/basophil channel
Basophils separated by being larger, stronger nuclear RNA/DNA Presence and hypergranularity
What do we notice about platelets?
Difficult to enumerate accurately
Impedance platelets
Cells are resistors = measure by impedance + count pulses
Optical platelets
Stained with same dye as reticulocytes, may be enumerated.
RNA/DNA content is stained
Fluorescent platelet count
Specialised fluorescent dye which stains internal structure of platelets
Extended time of counting = more accurate
Flow cytometry is
The preferred method for platelet count
Labelling platelets with marker
Raised while cells mean…
Bacterial infection (neutrophils + monocytes)
Raised lymphocyte counts mean…
Viral infection/Leukaemia
Low white cell counts…
Associated with some drugs
Large Red cells (macrocytosis) is associated with…
Liver disease
Vitamin B12
Folate deficiency
Small red cells (microcytosis) is associated with…
Iron deficiency
Haemoglobinopathy (thalassaemia)
Raised red cell count..
Cardiac problems
Low red cell count..,
Some anaemias
Low platelet counts (thrombocytopenia)
Bleeding
Liver disease
Marrow failure
Clotting problems
Immune disorders
High platelet counts…
Trauma
Post operative reaction
Clotting problems
Marrow disorders
Full blood count provides info relating to…
Blood cells (leucocytes)
Red blood cells (erythrocytes)
Platelets (thrombocytes)
Blood cells are called…
leucocytes
Red blood cells are called…
erythrocytes
Platelets are called…
thrombocytes
Automated analysers are…
Particle counters
= cells + extended info is provided using the characteristics of these cells.
