Haematocrit (Hematocrit)

Haematocrit definition

The volume of Red Blood Cells (RBC) in whole blood expressed in percentage is known as Haematocrit value. So in 100 ml. of blood, If there is 45ml. of RBC then the Haematocrit value of that blood is 45%. So your Haematocrit Test report will show the value as 45. This is also known as Packed Cell Volume (PCV).

Haematocrit Blood Test importance

Haematocrit blood test measures the percentage of RBC in your blood. This test is part of the Complete Blood Count Test. Haematocrit Value changes in different body conditions. So the value helps to determine your health condition, monitoring your progression of disease and how your body is responding to any ongoing treatment.

How Haematocrit Test is done?

Just like Hemoglobin Test, Haematocrit Test do not need any specific preparation. No restrictions in diet, drink. As a basic test you can do this test any time.

Haematocrit normal range according age and sex

At Birth 52
Childhood 36
Adolescence 40
Adult Man 47 (±6)
Adult Woman (menstruating) 40 (±6)
Adult Woman (postmenopausal) 42 (±6)
During Pregnancy 37 (±6)
Source: Harrison’s Principles of Internal Medicine

Haematocrit low causes

There are various causes of lower than normal level of Haematocrit. Some of the causes are

  • A deficiency of red blood cells (RBC) in your blood. So in Anemia the Haemotocrit level is low.
  • When your blood fluid is higher
  • Regular high bleeding in menstruation or blood loss due to any other reasons
  • Iron deficiency
  • Folate, Vitamin B12 deficiency
  • Micro elements Deficiency like Copper deficiency
  • Kidney Disease
  • Thyroid Problems
  • Use of some Drugs
  • In Leukemia and other white blood cell disorders
  • Bone Marrow disorder

Haematocrit high causes

When there is high RBC in your blood then it causes the high value of haematocrit. Some of the reasons of the high levels of haematocrit are

  • Dehydration or low fluid content in your blood
  • Heart problems
  • Living in high altitude (in this case high value of Haematocrit is normal)
  • Drugs like Erythropoietin
  • Carbon Monoxide Exposure
  • Smoking
  • Sleeping disorder (like Obstructive Sleep Apnea)
  • Lung problems
  • Bone Marrow problems


  1. William’s Hematology Book, 9th Edition
  2. Harrison’s Principles of Internal Medicine 20th edition, (pg.387)
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