Hematocrit Test: Procedure, Low, High and Norman Ranges, Results

A hematocrit test is a method of blood analysis. It contains red blood cells, white blood cells and platelets. These cells and platelets are suspended in a fluid known as plasma. (1)

Hematocrit refers to the percentage of red blood cells in the total amount of blood. Red blood cells are an essential component of your health. Think of them as your bloodstream subway system. They carry oxygen and nutrients at different places within your body. For you to remain in good health, your body must have the right proportion of red blood cells.

Your health care provider may prescribe a hematocrit, or Hct, If they think that you have too little or too much red blood cells.

Why would you get a hematocrit test?

A hematocrit test may assist your physician in diagnosing you with a specific condition, or it may help them determine the extent to which your body responds to some treatment. The test may be ordered for various reasons, but is most commonly used to verify:

  • leukemia
  • dehydration
  • anemia
  • dietary deficiencies

Your healthcare provider may have asked for a hematocrit test as part of your regular medical check-up or if you experience symptoms of a red blood cell disorder, like anemia or polycythemia vera. These include:

If your physician prescribes a complete blood count (CBC), the hematocrit test is included. The rest of the CBC tests are hemoglobin and reticulocyte count. Your doctor will examine your global blood test results to better understand your red blood cell levels.

How is the hematocrit test performed?

First, you’re going to receive a blood test. It will then be submitted to a laboratory for assessment.

Blood sample

A doctor may require a small blood sample to test your hematocrit. This blood may be collected from a finger stick or from a vein in the arm.

If the hematocrit test belongs to an CBC, a laboratory technician will take blood out of a vein, Most commonly from the inside of the elbow or back of the hand. The technician cleans the surface of your skin with an anti-septic and places an elastic band, or withers, around your arm to help the bloodstream swell.

A needle is then inserted into the vein and a blood sample is taken from one or more vials. The technician removes the elastic strip and covers the area with a bandage to prevent bleeding. A blood test may be slightly discomforting. When the needle punctures, you may feel a sting or pinch sensation.

Some people also experience faintness or dizziness when they see blood. You may have minor bruising, but it will wear off in a couple of days. The test will last just a few minutes and you will be able to resume your daily activities after completion. Your specimen will be sent to a laboratory for testing.


In the lab, your hematocrit is assessed with a centrifuge, which is a machine that rotates at a high rate to make sure the contents of your blood separate. A laboratory specialist will add a special anti-coagulant to prevent blood coagulation.

When the test tube was removed from the centrifuge, it was installed in 3 parts:

  • plasma
  • red blood cells
  • anticoagulant

Each component will be deposited in a different portion of the tube, with the red blood cells moving down the tube. The red blood cells are compared with each other with a guide that shows how much of your blood they make up.

What is a normal hematocrit level?

Whereas the lab testing the blood sample may have their own ranges, The ranges usually allowed for hematocrit depend on your gender and age. Typical ranges are the following:

  • Adult males: 38.8 to 50%.
  • adult females: 34.9% to 44.5%.

Children 15 years of age and younger have distinct ranges because their hematocrit rate changes rapidly with age. The specific laboratory that analyses the findings will determine the normal range of hematocrit for a child at a certain age. (2)

If your hematocrit rate is too low or too high, this may indicate different issues.

What if my hematocrit levels are too low?

Low hematocrit levels can be an indication of:

  • leukemia
  • lymphoma
  • bone marrow diseases
  • chronic inflammatory disease
  • nutritional deficiencies such as iron, folate and vitamin B-12
  • internal bleeding
  • hemolytic anemia
  • sickle cell anemia
  • kidney failure

What if my hematocrit levels are too high?

High hematocrit levels may result in:

Before you submit to the test, inform your physician if you have recently received a blood transfusion or if you are pregnant. Pregnancy may reduce your level of urea nitrogen in the blood (BUN) as a result of an increase in the amount of fluid in your body. You may also be affected by a recent blood transfusion. If you live above sea level, also affect.

Your physician will probably be comparing your hematocrit test results to the remaining elements of the CBC test and your general symptoms prior to making a diagnosis.

What are the risks of a hematocrit test?

There are no significant side effects or risks associated with a hematocrit test. You may experience bleeding or throbbing to the point where blood is collected. Tell your physician if you notice any swelling or bleeding that does not stop within a few minutes following the application of pressure at the puncture site.

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