Reasons, Procedure & Normal Ranges of Hematocrit Blood Test

Submitted on March 27, 2012

A hematocrit blood test is generally ordered as part of a complete blood count. It measures the percentage of volume of whole blood that is made up of red blood cells. The measurement depends on the size and number of the red blood cells.


Hematocrit testing helps evaluate the following:-
  • Anemia - to diagnose and treat it
  • Dehydration- recovery from this
  • Diet deficiency
  • Polycythemia - once again diagnosis and treatment of this
  • Leukemia
  • Blood transfusions decisions for those who are severely anemic
  • Any other medical condition

Normal Range

The normal ranges depend on age and sex of the patient. These are:
  • Newborns - 55%-68%
  • One week old child - 46%-65%
  • One month old child - 37%-49%
  • Three month old child - 30%-36%
  • One year old child - 29%-41%
  • Ten year old child - 36%-40%
  • Adult women - 38%-46%
  • Adult men-42%-54%

A decreased hematocrit is indicative of anemia. Hemoglobin will be low in this case. Anemia could be the result of blood loss (from injuries, surgery, bleeding), bone marrow problems (kidney failure, cancer, due to chemotherapy drugs), abnormal hematocrit (sickle cell anemia) or nutritional deficiencies (folate, iron, Vitamin B 12). More tests may be run to find out the exact cause of the anemia. Malignancies, liver cirrhosis, vitamin or mineral deficiencies, recent bleeding can also result in a low hematocrit count. During pregnancy the values are low due to the extra fluids in the body.  People who suffer from chronic illnesses such as rheumatoid arthritis or malnutrition or an inherited blood disorder are at a higher risk for abnormally low hematocrits.

The most common reason for an increased hematocrit level is dehydration. This will return to normal on consumption of adequate fluids. Abnormally higher levels of hematocrit are seen in chronic smokers as well as people who live at high altitudes. Certain tumors, polycythemia rubra vera (a bone marrow disorder) and lung disease are other reasons for a high hematorcit. If the drug Epogen has been misused by athletes for blood doping reasons, the hematocrit level will be high too.


The hematocrit test will be carried out in a laboratory. It cannot be performed at home. You will therefore not be able to get a hematocrit home test kit. During the hematocrit lab test a blood sample is taken from the patient and then the hematocrit is measured by an automated machine which makes several other measurements at the same time. It is calculated depending on the basis of the average volume of red blood cells and the amount of hemoglobin. Hematocrit test results will help the doctor decide on the right course of treatment for the patient