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Red blood cells and hematocrit

Red blood cells transport oxygen in the blood. If you don't have enough red blood cells, your oxygen supply decreases, causing certain bodily functions to become impaired. Conversely, if you have too many, your blood thickens and flows more slowly. A hematocrit test measures the proportion of red blood cells in the blood as a percentage of total blood volume.

The red blood cell count and hematocrit test are part of the complete blood count used to assess overall health.

What is the purpose of this test? These tests are done for several reasons:
  • To assess whether your blood cell production system is working properly
  • To check for an abnormal red blood cell count
  • To assess your level of hydration
How to prepare?
  • No preparation needed.
Reference values*
  • Red blood cell count in adult women: 3.50-5.00 x 1012/L
  • Red blood cell count in adult men: 4.00-5.50 x 1012/L
  • Hematocrit in adults: 38%-50%
Associated tests The other tests in a complete blood count are performed at the same time. These tests measure different parts and features of your blood, including the following:
How is it done? A blood sample is drawn, usually from a vein in the arm
How long before I get the results? Results are usually ready in a day. It may take longer to receive your results.
* These values are presented for information purposes only. As different laboratories may have different target values, the lab report usually specifies the values used for the test. It should also be noted that test results must be interpreted based on factors such as age, sex, and health condition. Values outside of this range may be considered normal for some individuals.

What does an abnormal test result mean?

Red blood cell count and hematocrit test results can't be interpreted on their own. Evaluating the results of the other tests typically carried out at the same time is essential to determine the possible cause of abnormal values.

High red blood cell count and hematocrit value:

  • Dehydration
  • Lung or heart disease
  • Certain cancers

Low red blood cell count and hematocrit value:

Indication of anemia caused by any of the following:

  • Red blood cell destruction
  • Abnormal red blood cell shape
  • Lack of certain minerals or vitamins
  • Bone marrow or kidney disorders
  • Chronic inflammatory diseases
  • Blood loss (e.g., digestive bleeding)

Medications that may affect test results

The use of certain medications can influence test results. Here are a few examples:

  • Human erythropoietin
  • Diuretics

What you should know before going for this test

When you go in for a blood test or any other medical exam, it's always a good idea to bring a complete list of any prescriptions, over-the-counter medications, or natural health products you're taking. Unless otherwise advised, it's best to take your medications as usual on blood test days. If in doubt, don't hesitate to talk to your healthcare professional.

© Copyright Vigilance Santé

The patient information leaflets are provided by Vigilance Santé Inc. This content is for information purposes only and does not in any manner whatsoever replace the opinion or advice of your health care professional. Always consult a health care professional before making a decision about your medication or treatment.

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