HomeMedicine & HealthDiagnostics & ImagingWhat is Complete Blood Count (CBC)?
Medicine & Health·2 min·Updated Mar 15, 2026

What is Complete Blood Count (CBC)?

Complete Blood Count

Quick Answer

A Complete Blood Count (CBC) is a common blood test that measures different components of your blood, including red blood cells, white blood cells, and platelets. It helps doctors assess your overall health and detect a variety of disorders, such as anemia and infection.

Overview

A Complete Blood Count (CBC) is a blood test that provides important information about the cells in your blood. It measures the number of red blood cells, which carry oxygen, white blood cells, which fight infection, and platelets, which help with blood clotting. By analyzing these components, healthcare providers can gain insights into your health and detect potential issues early on. The CBC works by taking a small sample of your blood, usually from a vein in your arm. This sample is then analyzed in a laboratory, where machines count the different types of cells and measure their characteristics. For example, the test can reveal if you have too few red blood cells, indicating anemia, or if your white blood cell count is high, suggesting an infection. Understanding your CBC results is crucial for diagnosing various conditions. For instance, if a patient feels fatigued and has a low red blood cell count, their doctor might investigate further for underlying causes like nutritional deficiencies or chronic diseases. In the context of diagnostics and imaging, a CBC is often one of the first tests performed when assessing a patient's health, providing a foundation for further testing if needed.


Frequently Asked Questions

A Complete Blood Count test measures several components of your blood, including red blood cells, white blood cells, and platelets. It also provides information about hemoglobin levels and hematocrit, which help assess your overall health.
A doctor may order a CBC to check for various health issues, such as anemia, infection, or other blood disorders. It is a routine test that can help identify problems before symptoms appear.
In most cases, no special preparation is needed for a CBC test. However, your doctor may advise you to avoid eating or drinking for a few hours before the test to ensure accurate results.