Other names: Haematocrit; Packed Cell Volume

The PCV test is used to measure the amount of cells in the blood; blood is made up of cells and plasma. The amount of cells in the blood is expressed as a percentage of the total volume of blood; for example, a PCV measurement of 50% means that there are 50 millilitres of cells per 100 millilitres of blood.

The PCV measurement may increase or decrease depending on the individual’s health; if they are dehydrated, the measurement will rise and the measurement will decrease if the individual has a condition, such as anaemia.

When is the test used?

The PCV test is usually ordered as part of the series of tests that make up the full blood count. The test is used to diagnose and monitor conditions including anaemia, polyctyhaemia and dehydration. The test may also be used to determine whether an individual is fit to have a blood transfusion; the test may also be repeated regularly to check whether the transfusion has worked effectively.

The test is usually ordered to monitor the condition of people who have been diagnosed with anaemia; it may also be used to monitor those with dehydration and persistent bleeding.

How is the test done?

The test is done by taking a sample of blood from the patient; in most cases, the sample is taken from a vein in the patient’s arm. A needle is inserted into the vein and the blood is drawn out and collected in a syringe. Once the sample has been collected, it will be bottled, labelled with the patient’s name and sent off to a laboratory for testing.

In children, a sample may be collected from the fingertip; in infants it may be collected from the heel. The samples are obtained by pricking the finger or the heel with a needle.

What do the test results mean?

A decreased PCV result usually indicates anaemia. A low PCV count may also indicate vitamin or mineral deficiencies, liver cirrhosis and bleeding episodes.

Increased PVC results are usually associated with dehydration; in most cases, the PCV result will return to normal once the individual has increased their fluid intake.

High PCV results may also be caused by polycythaemia vera, a condition which occurs when an individual has too many red blood cells; this is caused by a problem with the function of the bone marrow.

Living at high altitude usually increases PCV. Pregnancy usually causes PCV results to be slightly lower than normal.

Specific Blood Tests

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