The hematocrit test is an important test for estimating the average volume of red blood cells. Anticoagulated blood is used for hematocrit tests.
You can calculate mean corpuscular volume (MCV) with the help of HCT.
Hematocrit testing methods and procedure
There are two methods for calculating the hematocrit.
- Macro Method (Wintrobe’s Method)
- Micro Method
Wintrobe’s method of Hematocrit (macrohematocrit) test requirements, procedure , advantage and disadvantage
It is an old method of HCT estimation, now the micro method is used.
- Wintrobe tube
- Centrifuge (15 cm internal radius)
- Pasture pippet
MacroHematocrit testing Procedure
- Fill the tube up to the maks of 100 with EDTA anti-coagulated blood.
- Centrifuge the tube at 3500 rpm for 30 minutes.
- Carefully take the tube from the centrifuge and note the level of packed RBC (Buffy coat should not be included).
Note: If packed cell volume is above the 0.5 L/L, centrifuge again for 30 minutes.
Advantage of macrohematocrit method
- The same tube can be used for ESR (Erythrocyte Sedimentation Rate)
- It did not require a special centrifuge as micro mrethod.
DisAdventage macrohematocrit method
- The macro method requires a large amount of blood as compared to the micro method.
- Centrifugation time is long (30 mint).
- This method is not 100% accurate.
Microhematocrit method procedure, requirements, procedure , advantage and disadvantage
It is an advanced method of hematocrit calculation.
- 75 mm length with 1 mm bore longe tube.
- Microheamtocrit centrifuge
- Microhematocrit Reader
Microhematocrit method Procedure
- Fill the tube with blood.
- Seal one end of the tube with plasticine.
- Place the tube in the Microheamtocrit centrifuge.
- Centrifuge for 4 to 5 minutes.
- Take the tube from the centrifuge and place it in the microhematocrit Reader and note the packed cell volume (PCV).
Advantage of microhematocrit method
- Small quantity is sufficent for the test (Macro method need large).
- Less centrifuge time is requiered in micro-method.
- One than one sample can be run at a time.
- It is accurate as compare to Macro method.
DisAdventage of microhematocrit method
- It needs Microhematocrit Reader.
- Microheamtocrit centrifuge is necessary for the micro method.
Sources of error in Hematocrit test (PCV/ HCT)
- Sample collecting error.
- Incorrect amount of anti-coagulant.
- Incorrect filling of the tube.
- A clot in the sample.
- Hemolysis sample.
- Variation in the internal diameter or bore of the tube.
Give the possible variations in color of the plasma when performing hematocrit determination.
During hematocrit determination, the color of the plasma can vary based on several factors. Here are some possible variations:
- Pale or Straw-Colored: This is the typical color of normal plasma. It appears pale yellow or straw-colored.
- Pink or Reddish: If there is hemolysis (breakdown of red blood cells), the plasma may have a pink or reddish tinge. This can occur due to factors such as rough handling of the sample or certain medical conditions.
- Cloudy or Milky: In some cases, the plasma may appear cloudy or milky. This can be caused by increased lipid levels (lipemia) in the blood, which can occur after consuming a fatty meal or in certain medical conditions.
- Yellow or Jaundiced: If there is an excessive amount of bilirubin in the blood, the plasma can have a yellowish tinge. This is commonly seen in conditions such as jaundice or liver disease.
what is the difference between pcv and hct?
when anti-coagulated blood is centrifuged, red blood cells are packed at the bottom. These Red blood cells are expressed as the RBC volume of centrifuged blood. This call is called a PACKED CELL VOLUME (PCV).
On the other hand, when this Packed cell volume is expressed in percentage (%) of total centrifuged blood, it is called Hematocrit (HCT)
Low Hematocrit mean
Hematocrit link with Red blood cell concentration in the blood. When RBC increase, Hematocrit will raise. When RBC decrease, Heamtocrit will decrease. In case of anemia. hematocrit will be less than normal due to less quantity of red blood cells.
High Hematocrit mean
Hct will raise when red blood cells increase. Some diseases are like Polycythemia. Red blood cells increase, as a result, Hematocrit will increase.
what is the hematocrit test?
The hematocrit test measures the percentage of red blood cells in your blood. A small blood sample is taken and placed in a tube, which is then centrifuged.
what tube is appropriate for hematocrit testing?
The appropriate tube for hematocrit testing is a capillary tube. They are typically around 75 mm in length and have a diameter of about 1-1.5 mm.
Capillary tubes allow for the separation of blood components during centrifugation, enabling the measurement of the packed cell volume and determination of the hematocrit value.
what is a hematocrit test used for?
The hematocrit test is used to diagnose and monitor blood disorders, assess blood volume, monitor blood loss. It provides valuable information about red blood cell health.