5-pcv

Practical Physiology 5th Lab.

Packed Cell Volume P.C.V. (Haematocrit) and Blood indices

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Lab. no. 5: PCV (HCt.)

Principle: A volume of uncoagulated blood is centrifuged at high speed in a capillary tube. The level of packed cell is read directly from the graphic reader, reader and the reading is expressed as a percentage (%). (%)

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Lab. no. 5: PCV (Hct.)

Procedure:  Fill a heparinized capillary tube with blood to about 80 % of its length.  Seal one end of the capillary tube with sealing clay.  Place the capillary tube in a high speed centrifuge. The sealed end should be kept outside.  Place the cover of the centrifuge and begin centrifugation for (3-5) min. Read the percentage of packed cells directly from the graphic reader. [email protected]

Lab. no. 5: PCV (Hct.)

PCV is seen in haemoconcentration e.g.: dehydration, burns, and polycythemia. PCV is seen in conditions associated with hydremia e.g.: pregnancy and excessive administration of fluid.

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Lab. no. 5: PCV (Hct.)

-Normal (PCV) values:

 - at birth

- adult male

= 56 ±10 % = 47 ± 5 %

- adult female = 42 ± 5 % [email protected]

Lab. no. 5: PCV (Hct.)

Blood indices: • Mean corpuscular volume (MCV). • Mean Corpuscular Hb. (M.C.H.). • Mean Corpuscular Hb. Conc. (M.C.H.C.).

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Blood indices: 1. Mean corpuscular volume (MCV): Is the average volume of a single RBC in fimtoliters (fl = 10-15 Liter). M.C.V =

PCV / liter of blood RBC count / liter of blood

Normal M.C.V.= 86 – 96 fl. Normocyte * <86 fl. = Microcyte. * >96 fl. = Macrocyte. Examples of anaemia: a. Normocytic anaemia ------Haemorrhage. b. Microcytic anaemia -------Iron deficiency anaemia. c.Macrocytic anaemia -------Vitamin B12 deficiency anaemia. [email protected]

Blood indices: 2. Mean Corpuscular Haemoglobin (M.C.H.): Is an expression of average amount of Hb per cell in picograms (pg =10-12gm). M.C.H =

Hb conc./ liter

-Normal M.C.H.= M.C.H. 27-32 pg. Normochromic. * *

<27 pg. >32 pg.

Hypochromic anaemia(Iron deficiency). Hyperchromic anaemia(Vit.B12 deficiency).

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Blood indices: 3. Mean Corpuscular Hb. Conc (M.C.H.C.): Is the amount of Hb as a percentage of the volume of a corpuscle. M.C.H.C. =

Hb conc./ liter of blood PCV

-Normal M.C.H.C.= 33-36 g%

Normochromia.

<33 g% = Hypochromia. >36 g% = Hyperchromia.

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