A CBC or Complete Blood Count is a blood test that measures many different parts and features of your blood. It is a commonly performed lab test that can help detect or monitor many different health conditions. A CBC test measures the following:

• 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.

A CBC test can show unusual increases or decreases in cell counts, which might point to a medical condition that calls for more testing. For example, abnormal levels of red blood cells, hemoglobin, or hematocrit may be a sign of anemia, heart disease, or too little iron in your body. A CBC is usually performed by taking a blood sample, and there is no special preparation needed. The test is commonly used to diagnose and monitor numerous diseases. However, a CBC test usually doesnt give all the answers about a diagnosis, and results outside the expected range may or may not need follow-up.