Complete Blood Count

A complete blood count, or CBC, is a blood test that measures many different parts and features of your blood, including:

Red blood cells, which carry oxygen from your lungs to the rest of your body.

White blood cells, which fight infections and other diseases. There are five major types of white blood cells. A CBC test measures the total number of white cells in your blood. A different test called a CBC with differential measures the number of each type of these white blood cells.

Platelets, which stop bleeding by helping your blood to clot.

Hemoglobin, a protein in red blood cells that carries oxygen from your lungs to the rest of your body.

Hematocrit, a measurement of how much of your blood is made up of red blood cells.

Mean corpuscular volume (MCV), a measure of the average size of your red blood cells.