Hematocrit hema Flashcards
Volume of packed red blood cells that occupies a given volume of
whole blood after centrifugation of a blood sample
Also known as ____ or ____
Reported either as ___,___,___,___
Hematocrit
- Packed Cell Volume (PCV) or Erythrocyte Volume Fraction (EVF)
-percentage(%), cell volume percent (CV%), volume percent (Vol%) or in liters per liter (L/L)
Plasma
water, nutrients proteins hormones
Buffy coat
wbc, platelets
Hematocrit
RBC
Normal blood
37-47% hct female
42-52% hct male
depressed hct %
Anemia
elevated hct %
Polycythemia
HEMATOCRIT
DETERMINATION
Macro method ( Wintrobe method) & micro method (Adam’s Microhematocrit)
Adam’s Microhematocrit method
Procedure:
1. Fill two plain capillary tubes approximately three-quarters (3/4) full with blood anticoagulated with ___
> 2/3 filled, ____, filled portion ___
Length:___
Bore: ___
____ - for blood collected on anticoagulated tube
____ - for blood from skin puncture
- EDTA/heparin
-0.05 ml blood - 5 cm
- 7-7.5 cm
- 1.2 mm
- Non-heparinized (blue ring) capillary tube
- Heparinized (red ring) capillary tube
Seal the end of the tube with the colored ring using___
> Seal by placing the dry end into the tray with sealing compound at a __.
> Rotate the tube slightly and remove it from the tray
> The plug should be at least___ long
nonabsorbent sealing clay
90-degree angle
4 mm
Balance the tubes in a
microhematocrit centrifuge with the clay ends facing ___ , touching the rubber gasket
outside away from the center
Tighten the head cover on the
centrifuge and close the top. Centrifuge the tubes at ___ for ___.
10,000g to 15,000 g for 4-5 minutes
Determine the hematocrit by using a ___
microhematocrit reading device
The values of duplicate hematocrits
should agree within ___
1% (0.1 L/L)
HCT Reference Values
Conventional Unit:
Male: 40-54%
Female: 35-49%
HCT Reference Values
SI Unit:
Male: 0.40-0.54 L/L
Female: 0.35-0.49 L/L
Estimation of __ and ___ is possible on the basis of the hematocrit value under normal circumstances.
1% hematocrit - ___ Hemoglobin or ___ RBC/cumm
hemoglobin and red blood cell count
- 0.34 g/dL
- 107,000
INCREASED HCT
- the specimen was not mixed properly
- Insufficient centrifugation or a delay in reading results after
centrifugation - The buffy coat of the specimen should not be included in the hematocrit reading because this falsely elevates the result
- microhematocrit reader is
not used properly - The fluid loss associated with dehydration causes a decrease in plasma volume and falsely increases the hematocrit reading
DECREASED HCT
- Improper sealing of the capillary tube as a result of leakage of blood during centrifugation
- An increased concentration of anticoagulant (short draw in an
evacuated tube) - the specimen was not mixed properly
- microhematocrit reader is
not used properly - A temporarily low hematocrit reading may result immediately after a blood loss because plasma is replaced faster than are the RBCs
- Proper specimen collection is an important consideration. The
introduction of interstitial fluid from a skin puncture or the improper flushing of an intravenous catheter causes decreased hematocrit readings
Many disorders, such as __,__,__,__,__,___ may cause plasma to be trapped in the RBC layer even if the procedure is performed properly
sickle cell anemia, macrocytic anemias, hypochromic
anemias, spherocytosis, and thalassemia,
____: amount of plasma that still remains in the RBC portion after the microhematocrit has been spun.
Trapped Plasma
Trapping of the plasma causes the microhematocrit to be ___ to ____ higher than the value obtained using automated instruments that calculate the hematocrit and are unaffected by the trapped plasma
1% to 3% (0.01 to 0.03 L/L)
Automated Methods
1
2
( Coulter Counter, Autoanalyzer)
Hematocrit = __
RBC x MCV
This method utilizes the Wintrobe
tube
Length:___
Bore: ___
Has 2 calibrations
0-10 (Red) is used for ___
10-0 (White) used for __
Anticoagulant of choice: __
Wintrobe Method
11.5 cm
3 mm
Erythrocyte Sedimentation Rate (ESR)
hematocrit
Double oxalate
Procedure
1. Fill the Wintrobe tube with blood using a Pasteur pipette
2. Centrifuge the tube at___
3.Read the volume of packed red blood cells
4.Compute for the hematocrit level using the formula: ____
Wintrobe Method
3000 rpm for 30 minutes
Hematocrit = (height of packed RBC / height of whole blood used) x 100
Rule of Three
> This rule only applies to specimens that have __,___
RBC x 3 = Hgb
Hgb x 3 = Hct +/-3
- normocytic normochromic
RBCs
