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Normal hematocrit percentage in the blood

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Normal hematocrit percentage in the blood
Last update: 15/12/2020

What is the normal range of hematocrit?

The normal values for hematocrit vary with age and gender:

Adult men: 40 - 54%
Adult women: 36 - 48%
Boys over 15 years old: 40 - 51%
Girls over 15 years old: 36 - 45%
Children from 12 to 14 years old: 36 - 47%
Children from 5 to 12 years old: 35 - 44%
Children from 6 months to 5 years old: 33 - 44%
Children from 2 weeks to 6 months old: 27 - 45%
Newborns: 44 - 56%

Why normal levels can differ across different labs?

Each laboratory must establish its own normal ranges for hematocrit in the blood. These ranges depend on the makeup of the local population, the technologies used and the accuracy of the measurement. There may be also slight differences in the normal levels according to age, gender, race or ethnic origin, geographic region, diet, type of sample and other relevant status.

Your doctor will study the results along with your medical record, screenings, physical condition, symptoms and any other relevant information about your situation.

Some circumstances can alter the previous ranges:

  • The hematocrit slightly decreases in pregnancy due to an increase in plasma volume.
  • There is also a tendency toward lower hematocrit values in men and women older than 60 years of age.
  • Residents of high altitude have hematocrit levels above those observed at sea level. There may be an increase in normal range up to 7% in case of high-altitude population.

What is hematocrit?

Hematocrit (HCT) is the volume of red cells expressed as a percentage of the volume of whole blood in the sample. The hematocrit is sometimes also called the packed cell volume (PCV).

Red blood cells (RBC), also called erythrocytes, give the blood its characteristic red color.

If the number of RBC is below the normal range or the RBC are small in size (volume) there will be a low level of hemoglobin in the blood and the hematocrit will be below the normal percentage.

The hematocrit is determined indirectly from the number of RBCs (Red Blood Cell count) and the average size of RBCs (MCV) according to the following formula. MVC Refers to Mean Corpuscular Volume:

Hematocrit = RBC count x MCV

There is a close link between hematocrit and hemoglobin. Hemoglobin is an iron-based molecule type that carries oxygen to the cells of the body. Both are usually simultaneously increased or decreased.

There is a doping procedure called blood doping. It uses substances like EPO (Erythropoietin) to increase the hematocrit percentage in order to improve an athlete's performance.

What is hematocrit test used for?

The hematocrit percentage is usually requested in a general blood test to give information about your health. The hematocrit test is performed along with other RBC studies such as RBC count, hemoglobin, MCV (Mean Corpuscular Volume), MCH (Mean Corpuscular Hemoglobin), MCHC (Mean Corpuscular Hemoglobin Concentration) and RDW (red cell distribution width) for a better diagnosis.

A low percentage of hematocrit is usually seen at the same time that a low hemoglobin level. Therefore, decreased Hematocrit values are an indicator of anemia, a condition in which there is a reduction in the hemoglobin in the blood. A low hematocrit percentage is usually due to a low amount of RBC in the blood or because RBCs are destroyed faster than they can be made.

There are many types of anemia:

  • Iron deficiency anemia: It is the most common and it is due to an iron deficit.
  • Hemolytic anemia: It is caused by a fast destruction of RBCs. The destruction of red blood cells is called hemolysis.
  • Megaloblastic anemia: The cause is a lack of vitamin B12 or folic acid.
  • Aplastic anemia: Where the bone marrow cannot create enough blood cells.

As you can see, there are many types of anemia and only studying the hematocrit is not possible to know the type of anemia that you be suffering but it gives information about the degree of the anemia, if it is mild, moderate or severe.

A higher than normal hematocrit may indicate:

  • A high production of RBCs, usually related to a disorder called polycythemia vera.
  • A low plasma volume, usually related to dehydration (diarrhea, burns, etc.).

Therefore, the hematocrit test is useful to diagnose:

  • Anemia and the degree of the anemia severity.
  • Dehydration.
  • Polycythemia vera.

Where can I find more information about hematocrit percentage in the blood?

You can visit our pages about:

Which values are considered a normal hematocrit percentage in the blood?

The following values are considered to be normal values:

IMPORTANT: These levels are expressed in percentage. They are an example of a healthy woman of about 45 years old with no known disease and not taking any medication. The ranges can be different depending on the laboratory or on your personal circumstances.

Hematocrit
Normality
36 %36.1 %36.2 %36.3 %36.4 %36.5 %36.6 %36.7 %
36.8 %36.9 %37 %37.1 %37.2 %37.3 %37.4 %37.5 %
37.6 %37.7 %37.8 %37.9 %38 %38.1 %38.2 %38.3 %
38.4 %38.5 %38.6 %38.7 %38.8 %38.9 %39 %39.1 %
39.2 %39.3 %39.4 %39.5 %39.6 %39.7 %39.8 %39.9 %
40 %40.1 %40.2 %40.3 %40.4 %40.5 %40.6 %40.7 %
40.8 %40.9 %41 %41.1 %41.2 %41.3 %41.4 %41.5 %
41.6 %41.7 %41.8 %41.9 %42 %42.1 %42.2 %42.3 %
42.4 %42.5 %42.6 %42.7 %42.8 %42.9 %43 %43.1 %
43.2 %43.3 %43.4 %43.5 %43.6 %43.7 %43.8 %43.9 %
44 %44.1 %44.2 %44.3 %44.4 %44.5 %44.6 %44.7 %
44.8 %44.9 %45 %45.1 %45.2 %45.3 %45.4 %45.5 %
45.6 %45.7 %45.8 %45.9 %46 %46.1 %46.2 %46.3 %
46.4 %46.5 %46.6 %46.7 %46.8 %46.9 %47 %47.1 %
47.2 %47.3 %47.4 %47.5 %47.6 %47.7 %47.8 %47.9 %
48 %       
Medically reviewed by our Medical staff on 15/12/2020

Bibliography

  • Concise Book of Medical Laboratory Technology: Methods and Interpretations. 2nd Edition. 2015. Ramnik Sood. ISBN: 978-93-5152-333-8. Pag. 212.
  • A Manual of Laboratory and Diagnostic Test. 9th edition. Frances Fischbach. Marshall B. Dunning III. 2014. Pag 90. ISBN-10: 1451190891.
  • Essentials of Medical Laboratory Practice. Constance L. Lieseke, Elizabeth A. Zeibig. 2012. ISBN: 978-0-8036-1899-2 Pag: 299.
  • Laboratory tests and diagnostic procedures with nursing diagnoses (8th ed), Jane Vincent Corbett, Angela Denise Banks, ISBN: 978-0-13-237332-6, Pag. 27.

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