Quantification and Clinical Significance of Pack Cell Volume (PCV) or Hematocrit (HCT)

Hematocrit is routinely done in a hematology labs for the diagnosis of anemia. After the blood has been drawn and centrifuged at very high speed the volume which is occupied by Red Blood Cells (RBCs) is known as Pack cell volume (PCV) or Hematocrit (HCT).

Quantification of Hematological Methods for Hematocrit (HCT):

There are two major Methods for the Estimation of Hematocrit (HCT)

1. The Micro-Hematocrit Method
2. Automation Method

1. The Micro-Hematocrit Method:

Micro-hematocrit is performed on routine basis in the past but nowadays Automation is famous. This method required EDTA Collected blood and the instruments or equipments which are required to performed this method are

• A Capillary tube with internal diameter of 1mm and length 75mm.
• Micro-Hematocrit Centrifuge
• Reading Device

Micro-Hematocrit Procedure:

• In a venous blood which is drawn by aseptic technique, place a capillary tube which permit the blood to enter in the tube by a process known as capillary action. Leave the last 15mm unfilled of capillary tube.
• With the help of Modeling clay seal the tube and make sure that there should no air bubbles between the column of blood and the modeling clay
• Centrifuge the tube at 15000rmp for at least 5 minute by placing the tube in a micro-hematocrit centrifuge machine with sealed end to the outer rim.
• By using a micro-hematocrit reading device read the results.

Importance/Significance of Hematocrit (HCT):

• This test is used as a screening test for different types of anemias.
• Apart with estimation of Hemoglobin and Red cells count, Hematocrit is also used for the calculation of Red cells indices which have much more importance for the classification of Anemias.
• It may also be used as allusion/reference method for the assessment/calibrating, Automated Hematological analyzers.
• It can also give us a rough idea and guideline for the measurement of Hemoglobin.

Safety Precautions During the Measurement of Pack Cell Volume PCV/HCT:

• PCV and HCT should be measured within 6 Hours of Sample Collection because they can increase with the passage of storage time.
• Centrifuge Machine should be check on regular basis for speed and accuracy of the test.
• The Capillary tubes which are used for estimation of PCV and HCT must be best specification and Best Qualities.

2. Automation Method For the Measurement of PCV/HCT:

These machine are known for their best performance, accuracy and precision with a very tiny/minimal effort. They imply/involves the use of automated machine for the analysis of hematological parameters. One of the machine is Automated hematological analyzer which having the power to run Blood Counts and all major Hematology parameters.

Reference Ranges of HCT and PCV:

Gender HCT (%) PCV (L/L)
Male 45 ± 5 % 0.45 ± 0.05 L/L
Female 41 ± 5 % 0.41 ± 0.05 L/L

Clinical Importance of HCT and PCV:

High Hematocrit:

• Polycythemia
• Heart and Kidney Problems
• Dehydration
• Diarrhea
• Burns
• Smoking
• High Altitude

Low Hematocrit:

• Water Retention (Pregnancy, Edema)
• Hereditary Anemia
• Blood Loss (Menses, Bleeding and Internal Hemorrhage)
• Bone Marrow Insufficiency (Inflation with CLL, Cancer)
• Chronic Disease (Liver, Kidney and Rheumatoid arthritis)