Packed cell volume (PCV), also known as hematocrit, measures the volume of red blood cells in a blood sample. It is determined by centrifuging a tube of blood and measuring the percentage of blood volume occupied by red blood cells. The results are used along with other blood parameters like hemoglobin and red blood cell count to calculate red blood cell indices. These indices provide information about the size, hemoglobin content and concentration in red blood cells to help diagnose anemia and other blood disorders. Common indices include mean corpuscular volume, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration.

1. Packed cell volume (pcv) &Packed cell volume (pcv) &
blood indicesblood indices
ByBy
Mardeen farooqMardeen farooq
Shang xalidShang xalid
Karez abdulkhalqKarez abdulkhalq

2. Packed cell volume of whole bloodPacked cell volume of whole blood
 Hematocrit is difined as the volumeHematocrit is difined as the volume
accupied by erythrocytes in given volumeaccupied by erythrocytes in given volume
of the whole blood sampleof the whole blood sample
 The hematocrit may also be referred to asThe hematocrit may also be referred to as
packed cellpacked cell
volume (PCV)volume (PCV)

3.  Prenciple:Prenciple:
-Hematocrit is usually determined by spined a-Hematocrit is usually determined by spined a
blood-filled capillary tube in a centrifugeblood-filled capillary tube in a centrifuge
 Specimen:Specimen:
-Venous blood anticoagulated with EDTA or-Venous blood anticoagulated with EDTA or
capillary blood collected directly intocapillary blood collected directly into
heparinized capillary tubes can be used.heparinized capillary tubes can be used.
Specimens should be centrifuged within 6Specimens should be centrifuged within 6
houeres of collectionhoueres of collection
-Hemolized samples cannot be used for testing-Hemolized samples cannot be used for testing

4. Reagents and equipmentReagents and equipment
 Capillary tubes,hiparinized for finger sticksCapillary tubes,hiparinized for finger sticks
(red tip) or plain for anticoagulated blood(red tip) or plain for anticoagulated blood
(blue tip)(blue tip)
 Clay-type tube sealantClay-type tube sealant
 Microhematocrit centrifugeMicrohematocrit centrifuge
 Microhematocrit readerMicrohematocrit reader

5. procedureprocedure
1.1. Fill two capillary tubes approximately threeFill two capillary tubes approximately three
quarters full with blood anti-coagulated withquarters full with blood anti-coagulated with
EDTA or heparin. Alternatively, blood forEDTA or heparin. Alternatively, blood for
heparinized capillary tubes may be collectedheparinized capillary tubes may be collected
by capillary puncture. Wipe any excess bloodby capillary puncture. Wipe any excess blood
from the outside of the tubefrom the outside of the tube

6. 2. Seal the end of the tube with the colored ring2. Seal the end of the tube with the colored ring
with nonabsorbent claywith nonabsorbent clay
3. Balance the tubes in the centrifuge with the3. Balance the tubes in the centrifuge with the
clay ends facing the outside away from theclay ends facing the outside away from the
center, touching the rubber gasketcenter, touching the rubber gasket..

7. 4. Tighten the head cover on the centrifuge and4. Tighten the head cover on the centrifuge and
close the top. Activate the centrifuge for 5close the top. Activate the centrifuge for 5
minutes between 10,000 and 15,000rpmminutes between 10,000 and 15,000rpm
5. Determine the HCT by using a microhematocrit5. Determine the HCT by using a microhematocrit
reading device Read the level of RBCreading device Read the level of RBC
packing; do not include the buffy coatpacking; do not include the buffy coat
(leukocytes and platelets when reading.(leukocytes and platelets when reading.

8. Hematocrit readerHematocrit reader
 Reference ranges:Reference ranges:

NewbornNewborn 53-65%53-65%

Infant/childInfant/child 30-43%30-43%

Adult maleAdult male 42-52%42-52%

Adult femaleAdult female 37-47%37-47%

9. High Hematocrit LevelHigh Hematocrit Level
Some factors may cause a rise inSome factors may cause a rise in
hematocrit value such as:hematocrit value such as:
• PolycythemiaPolycythemia
• Heart or kidney problemsHeart or kidney problems
• Intake of anabolic steroidsIntake of anabolic steroids
• DehydrationDehydration
• DiareheaDiarehea
• Lung problemsLung problems
• BurnsBurns
• SmokingSmoking
• High altitudesHigh altitudes

10. Low Hematocrit LevelsLow Hematocrit Levels
The most common symptoms of low hematocrit levelsThe most common symptoms of low hematocrit levels
are:fatique,weakness,dizziness.Low hemoglobin levelsare:fatique,weakness,dizziness.Low hemoglobin levels
and pregnancy is commonly associated with aand pregnancy is commonly associated with a
decreased hematocrit range.decreased hematocrit range.
Other causes are:Other causes are:
• AnemiaAnemia
• HemolysisHemolysis
• Nutritional deficienciesNutritional deficiencies
• BleedingBleeding
• Renal failureRenal failure
• PregnancyPregnancy
• MedicationsMedications

11. Sources of errorSources of error
1.1. Improper sealing of the capillary tube.Improper sealing of the capillary tube.
2. An increased amount of anti-coagulant .2. An increased amount of anti-coagulant .
3.The time and speed of the centrifugation3.The time and speed of the centrifugation
and the time when the results are readand the time when the results are read
are very important.are very important.

12. 4. If too much time elapses between when the4. If too much time elapses between when the
centrifuge stops and the capillary tube iscentrifuge stops and the capillary tube is
removed.removed.
5. The buffy coat of the specimen should not be5. The buffy coat of the specimen should not be
included in the Hct reading.included in the Hct reading.
6. A decrease or increase in the readings may be6. A decrease or increase in the readings may be
seen if the microhematocrit reader is not usedseen if the microhematocrit reader is not used
properly.properly.

13. 7. A number7. A number of disorders such as:of disorders such as:

Sickle cell anemiaSickle cell anemia

Macrocytic anemia'sMacrocytic anemia's

Hypochromic anemia'sHypochromic anemia's

SpherocytosisSpherocytosis

TalassemiaTalassemia
may cause plasma to be trapped in themay cause plasma to be trapped in the
erythrocytes even if the procedure waserythrocytes even if the procedure was
performed properly.performed properly.

14. Red blood cellRed blood cell
indicesindices

15.  Red blood cell indicesRed blood cell indices (RBC) indices are(RBC) indices are
part of the complete blood count (CBC) test.part of the complete blood count (CBC) test.
They are used to diagnose the cause of anemiaThey are used to diagnose the cause of anemia
, a condition which there are too few red blood, a condition which there are too few red blood
cellscells
 are measurements that describe the size andare measurements that describe the size and
oxygencarrying protein (hemoglobin) content ofoxygencarrying protein (hemoglobin) content of
red blood cells.red blood cells.

16.  The relationships between the hematocrit, theThe relationships between the hematocrit, the
hemoglobin level, and the RBC are convertedhemoglobin level, and the RBC are converted
to red blood cell indices through mathematicalto red blood cell indices through mathematical
formulasformulas
 The indices include these measurements:The indices include these measurements:
mean corpuscular volumemean corpuscular volume
(MCV) . mean corpuscular hemoglobin(MCV) . mean corpuscular hemoglobin
(MCH) . mean corpuscular hemoglobin(MCH) . mean corpuscular hemoglobin
concentration (MCHC).concentration (MCHC).

17. Mean corpusculer volume (MCV)Mean corpusculer volume (MCV)
 TheThe MCVMCV is the average volume of theis the average volume of the
RBC in femtoliters (fL), or 10^-15L:RBC in femtoliters (fL), or 10^-15L:
 MCV = Hct (%) X 10 / RBC count (10MCV = Hct (%) X 10 / RBC count (10-12-12
/L)/L)..
 Cells of normal size (MCV is 80-100fL) areCells of normal size (MCV is 80-100fL) are
called normocytic, smaller cells arecalled normocytic, smaller cells are
microcytic, and larger cells are macrocyticmicrocytic, and larger cells are macrocytic

19. Mean corpusculer hemoglobinMean corpusculer hemoglobin
(MCH)(MCH)
 TheThe MCHMCH is the average weight of Hb inis the average weight of Hb in
an RBC, expressed in the units ofan RBC, expressed in the units of
picograms (pg), or 10^-12g:picograms (pg), or 10^-12g:
 MCH = HbMCH = Hb (g/dL) X 10 / RBC count (1012/L).(g/dL) X 10 / RBC count (1012/L).
 The reference range for adults is 28-32pg.The reference range for adults is 28-32pg.
 The MCH is not generally considered inThe MCH is not generally considered in
the classification of anemia's.the classification of anemia's.

20. Mean corpusculer hemoglobinMean corpusculer hemoglobin
concentration (MCHC)concentration (MCHC)
 TheThe MCHCMCHC is the average concentrationis the average concentration
of Hb in each individual erythrocyte.of Hb in each individual erythrocyte.
 units used are gram per deciliter (formerlyunits used are gram per deciliter (formerly
referred to as a percentage).referred to as a percentage).
 MCHC = Hb (g/dL) X 100 / Hct (%).MCHC = Hb (g/dL) X 100 / Hct (%).
 Values of normochromic cells range fromValues of normochromic cells range from
32 to 37g/dL.32 to 37g/dL.

21.  Hypochromic cells are less than 32g/dL, andHypochromic cells are less than 32g/dL, and
those of hyperchromic cells are greater thanthose of hyperchromic cells are greater than
37g/dL.37g/dL.
 Hypochromic erythrocytes occur inHypochromic erythrocytes occur in
thalassemia and iron deficiency.thalassemia and iron deficiency.
 Because there is a physical limit to theBecause there is a physical limit to the
amount of hemoglobin that can fit in a cell,amount of hemoglobin that can fit in a cell,
there is no hyperchromic category, a cell doesthere is no hyperchromic category, a cell does
not really contain more than 37g/dL of Hb, butnot really contain more than 37g/dL of Hb, but
its shape may have become spherocytic,its shape may have become spherocytic,
making the cell appear full.making the cell appear full.

23. Thank youThank you
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