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Hematocrit levels – Low, High, Normal Range


Hematocrit offers a general indication about the count of red blood cells occurring in the bloodstream. The hematocrit range provides information about the volume of red blood cells in blood. It displays data about the space taken by RBCs in a particular volume of blood. The measures of hematocrit values are always taken as percentages.

For example, if an adult male has a hematocrit value of 46 percent, then it indicates that 46 milliliters of red blood cells are present in a blood sample measuring 100 milliliters. Blood is majorly made of white blood cells, plasma, and RBCs. The red blood cells and white blood cells stay afloat in blood and can be seen circulating the body along with the bloodstream.It is understood that a measure of hematocrit is directly proportional to the number of RBCs. Hence, a low hematocrit value points to a low red blood cells count.

About 55 percent of the total blood volume is made up of plasma. It consists of dissolved proteins and glucose. Therefore, an increase or decrease in the red blood cells percentage with regards to the volume of plasma, is an indicator of many underlying health abnormalities. All this can be ascertained through a hematocrit test.

The normal hematocrit value is 40 percent for women and 45 percent for men. The hematocrit measure is considered as a vital component of a complete blood count test, along with the WBC count, the concentration of hemoglobin, and the platelet count. In mammals, hematocrit is not dependent on the size of the body.

How is it Done?

The hematocrit value is generally measured from a sample of blood with the help of an automated medical device that simultaneously carries out many other measurements.

A majority of these devices do not measure the hematocrit directly. It is instead calculated after taking into account the average volume of red blood cells and the quantity of hemoglobin. It is also possible to determine the hematocritvalue via a manual method that uses a centrifuge.When a sample of blood present in a tube is centrifuged, then the red blood cells tend to stack at the bottom of the tube. The proportion of RBCs to the total volume of blood can then be measured visually.

The Hematocrit Range

The hematocrit measure for either of the sexes is not the same. The test will provide different values according to the gender of the patient. It has been noted that the hematocrit value in men is greater than women. The hematocrit value also changes with varying age-groups. Adults and children will show different hematocrit values in the test.

Listed below is the hematocrit range according to gender and age-groups.

Hematocrit Measure in Adults:

  • The hematocrit value in women is normally observed to fall between 37 and 48 percent
  • In men, it generally falls in the range between 41 and 50 percent
  • It is important to remember that the above listed hematocrit values may slightly change as per the standards and machinery used to carry out the test in different labs. According to certain laboratories, the normal levels of hematocrit in men range between 40.7 and 50.3 percent, while it fluctuates between 36.1 to 44.3 percent in women.

Hematocrit Levels in Children:

  • A newly born baby that is just a few days old will have a hematocrit reading that falls between 42 and 65 percent
  • It is understood that the normal hematocrit measure of a baby that is two months old should range between 28 and 55 percent.
  • A 3-month old baby will show a hematocrit value that ranges between 30 to 36 percent.
  • Children belonging to the 6 to 12 years age group should have a hematocrit reading that ranges between 35 percent and 46 percent.
  • The hematocrit values of a ten year old child may fluctuate between 36 percent and 40 percent
  • A healthy boy who falls in the age group between 12 to 18 years may have a hematocrit reading value falling between 36 percent and 49 percent.
  • A healthy girl who is older than 12 years but younger than 18 years is most likely to show hematocrit values ranging from 36 percent to 46 percent.

It is important to note that the hematocrit levels have a tendency to vary with age. However, the normal range of hematocrit never goes over 70 percent.

High Values of Hematocrit

When high hematocrit values occur for long periods of time, then it signifies presence of underlying health problems. High hematocrit measures may occur due to:

  • Low levels of fluids in the body causes dehydration. The condition ultimately results in depletion of plasma levels in the blood which then leads to high hematocrit measures. Consume lots of water and fluids to treat dehydration.
  • Loss of fluids from the body can also occur due to diarrhea which causes watery stools. This can then lead to dehydration and eventually high hematocrit values.
  • Burns and other serious injuries can lead to increased loss of blood from the body. This results in depletion of plasma levels in blood, which in turn causes the hematocrit readings to go up above normal.
  • Diminished quantity of oxygen in the blood due to lung abnormalities, high altitudes, or excessive smoking, can trigger the increased production of red blood cells by the kidneys. This leads to an increase in the hematocrit levels.
  • Erythrocytosis is a medical condition that causes elevated RBC count. As the latter is directly proportional to hematocrit level, its value also rises subsequently.
  • Intake of anabolic steroids and blood disorders can also elevate the hematocrit levels.

Low Hematocrit

Low hematocrit values may arise due to:

  • Anemia, which lowers the RBC numbers thereby lowering the hematocrit values
  • Deficits in intake of essential nutrients like vitamin B12, iron, and folate can lower the RBC count, eventually causing the hematocrit levels to drop below normal.
  • Renal failure can lead to impaired kidney function, which results in lowered RBC production, thereby lowering the hematocrit levels. RBC numbers can also decrease due to use of chemotherapy medications.
  • Hemolysis is a condition which causes death of RBCs, thereby depleting their count and leading to a lowered hematocrit value.

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