total count
DESCRIPTION
TRANSCRIPT
TOTAL LEUKOCYTE COUNT
Dr.Gopala Krishnan.B.Yadav
It is a blood test to measure the number of white blood cells
It is a blood test to measure the number of white blood cells
Normal range
category Range / microlitre
adults 4000-10,000
birth 10,000-25,000
1-3yr 6000-18,000
4-7yr 6000-15,000
8-12yr 45000-13,500
Alteration in number and type of leukocytes is often associated with disease process & hence the count is informative
LEUCOCYTOSIS
Infections Malignancy like leukemia Severe emotional or physical stress Pregnancy
LEUCOPENIA
Infectionsbacterial-(typhoid,paratyphoid)viral(hepatitis)protozoa(malaria)
Some cases of leukemia Primary bone marrow depression
(Aplastic anaemia) Secondary bone marrow depression
(drugs,radiation) anaemia ( megaloblastic)
LETS COUNT…
SPECIMENS
Double oxalated or EDTA blood Capillary blood
REQUIREMENTS
Microscope Hemocytometer Wbc diluting fluid
HEMOCYTOMETER
Hemo: blood Cyto: cell Meter: measurement/counter
Thus, it is an instrument used to count the blood cells.
It includes:a) Neubauer’s slideb) Cover slipc) RBC pipetted) WBC pipette
NEUBAUER’S SLIDE
It is the name given to a thick glass slide . In the centre of the slide, there is an H- shaped groove. On the two sides of the central horizontal bar, there are scales for counting the blood cells The depth of the scales is 1/10mm or 0.1mm.
NEUBAUER’S CHAMBER
Neubauer’s slide with a cover slip over it, is called a Neubauer’s chamber
Four corner squares are meant for WBC counting.
Total = 64 small squares
WBC PIPETTE
It has a white bead It has graduations upto mark 11 Size of bulb is smaller Size of lumen is larger
WBC DILUTING FLUID:
It is prepared as follows: a) Glacial acetic acid: 2.0 ml b) 1 % (w/v) gentian violet: 1.0 ml c) Distilled water: 97 ml
PRINCIPLE
The glacial acetic acid lyses the red cells while the gentian violet slightly stains the nuclei of the leukocytes.
The blood specimen is diluted 1:20 in a WBC pipette with the diluting fluid.
The cells are counted under low power of the micro scope by using a counting chamber.
The number of cells in undiluted blood are reported per cu mm (µl) of whole blood
PROCEDURE
Draw blood up to 0.5 mark of a WBC pipette.
Carefully, wipe excess blood outside the pipette by using cotton.
Draw diluting fluid up to 11 mark. Mix the contents in the pipette and
after five minutes by discarding few drops, fill the counting chamber and allow the cells to settle for two to three minutes.
FOCUSING
4X to see the general formation of slide.
10X for WBC counting
COUNTING RULE
Do not count cells touchingBottom lineRight line This is to avoid double counting.
WBC COUNTING
DILUTION FACTOR
0.5 part of blood is mixed in 10 parts of fluid
So, 1 part of blood is in 20 parts of fluidThus, dilution factor for WBC counting is
20.
CALCULATION OF THE VOLUME OF WBC SQUARES
Length of one small square = 1/4mm Width of one small square = 1/4mm Depth of one small square = 1/10mm Volume of one small square = 1/4 x 1/4
x 1/10 = 1/160mm³
WBC COUNTING
Total no. of WBCs in 64 smallest squares = X No. of WBCs in one smallest square = X/64 Volume of one smallest square = 1/160mm³ No. of WBCs in 1/160mm³ = X/64 No. of WBCs in 1mm³ = X/64 x 160 No. of WBCs in 20 times diluted blood = X/64
x 160 No. of WBCs in undiluted blood = X/64 x 160
x 20/mm³ = X x 50/mm³