Complete Blood Count (CBC) Test

The CBC is a common screening test that measures red cells, white cells, hemoglobin, hematocrit, and platelets.

The complete blood count (CBC) is one of the most commonly ordered blood tests. It measures the cellular components of blood and is often used as a general screening test.

What it measures

  • Red blood cells (RBC), hemoglobin, hematocrit
  • Red cell indices (MCV, MCH, MCHC, RDW)
  • White blood cells (WBC) and a differential count
  • Platelets

When it may be ordered

A CBC may be ordered as part of a routine health check or to help evaluate symptoms such as fatigue, fever, unexplained bruising, or recurrent infections.

See hemoglobin for a deeper look at the most commonly discussed value on the CBC.