Packed cell volume (pcv) & Packed cell volume (pcv) & blood indicesblood indices

ByByMardeen farooqMardeen farooq

Shang xalidShang xalidKarez abdulkhalqKarez abdulkhalq

Packed cell volume of whole bloodPacked cell volume of whole blood

Hematocrit is difined as the volume Hematocrit is difined as the volume accupied by erythrocytes in given volume accupied by erythrocytes in given volume of the whole blood sampleof the whole blood sample

The hematocrit may also be referred to as The hematocrit may also be referred to as packed cell packed cell

volume (PCV)volume (PCV)

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 into capillary blood collected directly into heparinized capillary tubes can be used. heparinized capillary tubes can be used. Specimens should be centrifuged within 6 Specimens should be centrifuged within 6 houeres of collectionhoueres of collection

-Hemolized samples cannot be used for testing-Hemolized samples cannot be used for testing

Reagents and equipmentReagents and equipment

Capillary tubes,hiparinized for finger sticks Capillary 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

procedureprocedure1.1. Fill two capillary tubes approximately three Fill two capillary tubes approximately three

quarters full with blood anti-coagulated with quarters full with blood anti-coagulated with EDTA or heparin. Alternatively, blood for EDTA or heparin. Alternatively, blood for heparinized capillary tubes may be collected heparinized capillary tubes may be collected by capillary puncture. Wipe any excess blood by capillary puncture. Wipe any excess blood from the outside of the tubefrom the outside of the tube

2. Seal the end of the tube with the colored ring 2. Seal the end of the tube with the colored ring with nonabsorbent claywith nonabsorbent clay

3. Balance the tubes in the centrifuge with the 3. Balance the tubes in the centrifuge with the clay ends facing the outside away from the clay ends facing the outside away from the center, touching the rubber gasketcenter, touching the rubber gasket..

4. Tighten the head cover on the centrifuge and 4. Tighten the head cover on the centrifuge and close the top. Activate the centrifuge for 5 close 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 microhematocrit 5. Determine the HCT by using a microhematocrit reading device Read the level of RBC reading device Read the level of RBC packing; do not include the buffy coat packing; do not include the buffy coat (leukocytes and platelets when reading.(leukocytes and platelets when reading.

Hematocrit readerHematocrit reader

Reference ranges:Reference ranges:

NewbornNewborn 53-65% 53-65% Infant/child Infant/child 30-43% 30-43% Adult male Adult male 42-52% 42-52% Adult female Adult female 37-47% 37-47%

High Hematocrit LevelHigh Hematocrit LevelSome factors may cause a rise in Some 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 steroids Intake of anabolic steroids • DehydrationDehydration• DiareheaDiarehea• Lung problemsLung problems• BurnsBurns• SmokingSmoking• High altitudesHigh altitudes

Low Hematocrit LevelsLow Hematocrit LevelsThe most common symptoms of low hematocrit levels The most common symptoms of low hematocrit levels

are:fatique,weakness,dizziness.Low hemoglobin levels are:fatique,weakness,dizziness.Low hemoglobin levels and pregnancy is commonly associated with a and 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

Sources of errorSources of error1.1. 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 centrifugation 3.The time and speed of the centrifugation and the time when the results are read and the time when the results are read are very important.are very important.

4. If too much time elapses between when the 4. If too much time elapses between when the centrifuge stops and the capillary tube is centrifuge stops and the capillary tube is removed.removed.

5. The buffy coat of the specimen should not be 5. 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 be 6. A decrease or increase in the readings may be seen if the microhematocrit reader is not used seen if the microhematocrit reader is not used properly.properly.

7. A number7. A number of disorders such as: of disorders such as: Sickle cell anemia Sickle cell anemia Macrocytic anemia's Macrocytic anemia's Hypochromic anemia's Hypochromic anemia's Spherocytosis Spherocytosis Talassemia Talassemia may cause plasma to be trapped in the may cause plasma to be trapped in the

erythrocytes even if the procedure waserythrocytes even if the procedure was performed properly.performed properly.

Red blood cell Red blood cell indicesindices

Red blood cell indices Red 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 anemia They 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 cells cells

are measurements that describe the size and are measurements that describe the size and oxygencarrying protein (hemoglobin) content of oxygencarrying protein (hemoglobin) content of red blood cells.red blood cells.

The relationships between the hematocrit, the The relationships between the hematocrit, the hemoglobin level, and the RBC are converted hemoglobin level, and the RBC are converted to red blood cell indices through mathematical to red blood cell indices through mathematical formulasformulas

The indices include these measurements: The indices include these measurements: mean corpuscular volume mean corpuscular volume (MCV) . mean corpuscular hemoglobin (MCV) . mean corpuscular hemoglobin (MCH) . mean corpuscular hemoglobin (MCH) . mean corpuscular hemoglobin concentration (MCHC).concentration (MCHC).

Mean corpusculer volume (MCV)Mean corpusculer volume (MCV)

The The MCVMCV is the average volume of the is 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) are Cells of normal size (MCV is 80-100fL) are called normocytic, smaller cells are called normocytic, smaller cells are microcytic, and larger cells are macrocyticmicrocytic, and larger cells are macrocytic

Mean corpusculer hemoglobin Mean corpusculer hemoglobin (MCH)(MCH)

The The MCHMCH is the average weight of Hb in is the average weight of Hb in an RBC, expressed in the units of an 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 in The MCH is not generally considered in

the classification of anemia's.the classification of anemia's.

Mean corpusculer hemoglobin Mean corpusculer hemoglobin concentration (MCHC)concentration (MCHC)

The The MCHCMCHC is the average concentration of is the average concentration of Hb in each individual erythrocyte.Hb in each individual erythrocyte.

units used are gram per deciliter (formerly units 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 from Values of normochromic cells range from 32 to 37g/dL.32 to 37g/dL.

Hypochromic cells are less than 32g/dL, and Hypochromic cells are less than 32g/dL, and those of hyperchromic cells are greater than those of hyperchromic cells are greater than 37g/dL.37g/dL.

Hypochromic erythrocytes occur in Hypochromic erythrocytes occur in thalassemia and iron deficiency.thalassemia and iron deficiency.

Because there is a physical limit to the amount Because there is a physical limit to the amount of hemoglobin that can fit in a cell, there is no of hemoglobin that can fit in a cell, there is no hyperchromic category, a cell does not really hyperchromic category, a cell does not really contain more than 37g/dL of Hb, but its shape contain more than 37g/dL of Hb, but its shape may have become spherocytic, making the may have become spherocytic, making the cell appear full.cell appear full.

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