TRACK Flashcards
What is the definition of the FBC?
The enumeration and differentiation of white blood cells, measurement of haemoglobin, enumeration of platelets and red cells with the analysis of red cell indices
What sample type is needed for the track
EDTA anticoagulated whole blood
What track system is used
Sysmex XN analysers on XN 9000 track system
What are the three wbc chanels called
WNR
WDF
WPC
How does the WNR channel work
§ The enumeration of white blood cells, basophils, nucleated red blood cells and debris
§ Makes use of Lysercell WNR to lyse the red cells and shrink nucleated cells so Fluorocell WNR reagent can stain the intracellular components of cells
Basophils are relatively resistant to the Lysercell, hence their separation from the WBC population
How does the WDF channel work
§ Fluorescence flow cytometry for the WBC differential
§ Utilises Lysercell WDF to lyse the WBC membranes making them permeable to the Fluorocell WDF which stains the internal structure of cells enabling a differential count
§ Differential groups cells into lymphs, monos, neuts, eos, basos, immature granulocytes and debris
§ Flagging algorithms effectively support the ID of myeloid or lymphatic malignancy
IG count provides highly sensitive detection of WBC abnormalities
How does the WPC channel work
§ Highly sensitivity and specific chanel for white precursor cells
§ A reflex test which allows for the identification of abnormal white blood cells through the detection of an abnormal lipid composition in the cell membranes
§ Lysercell WPC targets the lipid on the cell membranes, enabling Fluorocell WPC to permeate and stain the internal structure
This analysis is triggered by an abnormal finding in the initial CBC + DIFF analysis and a special rule set for reflex testing
How is Haemoglobin Measured?
-> need more information
○ Haemoglobin is directly measured by spectrophotometry
○ SLS-HGB method adapted to be cyanide-free
Cyanide-free HB measurement
How are the red cells counted
○ RBC + PLT dilution is injected into the RBC PLT detector
○ The sample then passes through the middle of the aperature where it is hydrodynamically focused to ensure laminar flow
§ This ensures no cell is counted twice i.e. cells in single file
○ As the cells move through the aperture they cause an electrical resistance which is recorded as an impedence pulse
§ The size of the cell is proportional to the pulse height
The collective of these pulses produce the RBC histogram
How are platelets counted
○ The platelet histogram is generated using the same method as the RBCs
§ Hydrodynamically focused sample in diluent to ensure laminar flow
§ Electrical resistance pulse recorded
§ Impedence platelet count
Direct measurement using the Laser flow cell
What is MCV
Mean Cell Volume -> derived from the RBC size distribution data
What is RDW
Red cell distribution width -> derived from the RBC size distribution data
What is HCT
Haematocrit/packed cell volume -> the ratio of blood cells to plasma and is expressed on the whole blood volume, calculated from the red cell count and the MCV (RBC x MCV)
What is MCH
Mean Cell Haemoglobin -> calculated -> a function of cell volume -> measures the concentrationof Hb in each cell -> calculated from the Haemoglobin divided by the red blood cell count x 10 (HB/RCC x 10)
What is MCHC
Mean Cell Haemoglobin Concentration -> calculated -> measures the amount of Haemoglobin in 100ml of red blood cells -> calculated from the Haemoglobin divided by the Hct (Hb/Hct)
