A complete blood count (CBC) with differential is a commonly performed blood test that provides valuable information about the composition of your blood. It can help diagnose a wide range of medical conditions, including anemia, infections, inflammatory disorders, and certain types of cancer.

The CBC assesses oxygen-carrying capacity by measuring the number, size, and shape of red blood cells; hemoglobin, the protein in red blood cells that transports oxygen; and hematocrit, the volume of red blood cells compared to total blood volume. It also measures the total number of white blood cells, which are a vital component of the immune system, and platelets, which play a crucial role in clotting.

The “differential” part of the test breaks down the five specific types of white blood cells: neutrophils, lymphocytes, monocytes, eosinophils, and basophils. This information assists in determining the underlying cause of an abnormal total white blood cell count. (For example, an increase in neutrophils may indicate a bacterial infection, while a rise in lymphocytes could suggest a viral infection.)

Who should take this test?

A CBC with differential is typically recommended for individuals who are exhibiting symptoms or clinical signs of infections, inflammatory conditions, anemia, blood disorders, or other health issues that might involve abnormalities in white blood cell types or counts. It may also be ordered as part of a routine health check.

What is included in this test?

This blood test screens for:

• Total red blood cells
• Mean corpuscular volume (the average size of red blood cells)
• Red cell distribution width (a measure of the variation in size and shape of red blood cells)
• Hematocrit (the volume of red blood cells compared to total blood volume)
• Hemoglobin
• Mean corpuscular hemoglobin (the average amount of hemoglobin in each red blood cell)
• Mean corpuscular hemoglobin concentration (the concentration of hemoglobin in each red blood cell)
• Total white blood cells
• Percentage and absolute differential counts (for neutrophils, lymphocytes, monocytes, eosinophils, and basophils)
• Total platelets

How will taking this test benefit me?

This test helps healthcare providers gain specific insights into your body's immune response and pinpoint the underlying cause of illness, thereby guiding treatment decisions.