What is a hematocrit test?

A hematocrit is a simple blood test done to measure the red blood cells in a person’s blood. Red blood cells (erythrocytes) are important because they carry oxygen through your body. A low or high red blood cell count can indicate a medical condition or disease.

The hematocrit test determines the number of red blood cells.

Why is a hematocrit test needed?

A hematocrit test is needed to check for the proportion of red blood cells. A low red blood cell count, or low hematocrit, indicates anemia. Suspected anemia is the most common reason for hematocrit testing.

A hematocrit is sometimes called a HCT. The hematocrit is calculated from the number of red blood cells in a sample of blood.

What is anemia?

Anemia is a condition in which the body does not have enough red blood cells to carry oxygen through the body. It can have many causes, including iron and vitamin deficiency.

Symptoms of anemia include:

  • Tiredness
  • Headaches
  • Trouble concentrating
  • Cold hands and feet
  • Fatigue
  • Shortness of breath
  • Chest pain
  • Dizziness or lightheadedness

Last reviewed by a Cleveland Clinic medical professional on 01/12/2018.


  • Billett HH. Hemoglobin and Hematocrit. In: Walker HK, Hall WD, Hurst JW, editors. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition. Boston: Butterworths; 1990. Chapter 151. Accessed 2/13/2018.

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