Why it's done

A hematocrit test is part of a complete blood count (CBC). Measuring the proportion of red blood cells in your blood can help your doctor make a diagnosis or monitor your response to a treatment.

A lower than normal hematocrit can indicate:

  • An insufficient supply of healthy red blood cells (anemia)
  • A large number of white blood cells due to long-term illness, infection or a white blood cell disorder such as leukemia or lymphoma
  • Vitamin or mineral deficiencies
  • Recent or long-term blood loss

A higher than normal hematocrit can indicate:

  • Dehydration
  • A disorder, such as polycythemia vera, that causes your body to produce too many red blood cells
  • Lung or heart disease
May 26, 2016
References
  1. Sandoval C. Approach to the child with anemia. http://www.uptodate.com/home. Accessed March 24, 2016.
  2. Schrier SL. Approach to the adult patient with anemia. http://www.uptodate.com/home. Accessed March 24, 2016.
  3. Types of blood tests. National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics/bdt/types. Accessed March 24, 2016.
  4. Tefferi A. Diagnostic approach to the patient with polycythemia. http://www.uptodate.com/home. Accessed March 24, 2016.
  5. Hoffman R, et al. The polycythemias. In: Hematology: Basic Principles and Practice. 6th ed. Philadelphia, Pa.: Saunders Elsevier; 2013. http://www.clinicalkey.com. Accessed March 24, 2016.
  6. CBC with differential, blood. Mayo Medical Laboratories. http://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/9109. Accessed March 24, 2016.