Complete Blood Count (CBC)

A complete blood count (CBC) is a common blood test that measures various components of the blood to diagnose and monitor a wide range of health conditions.

Purpose

The purpose of a CBC is to:

  • Evaluate the overall health of the body
  • Diagnose and monitor blood disorders, such as anemia, bleeding disorders, and blood cancers
  • Monitor the effectiveness of treatments for blood disorders
  • Screen for underlying medical conditions, such as infections, inflammation, and immune system disorders

Components Measured

A CBC measures the following components of the blood:

  • Red Blood Cell (RBC) Count: The number of red blood cells in the blood, which carry oxygen to the body's tissues.
  • Hemoglobin (Hb): The amount of hemoglobin in the blood, which is a protein in red blood cells that carries oxygen.
  • Hematocrit (Hct): The percentage of red blood cells in the blood.
  • White Blood Cell (WBC) Count: The number of white blood cells in the blood, which help fight infections and diseases.
  • Differential Count: The proportion of different types of white blood cells, including neutrophils, lymphocytes, monocytes, eosinophils, and basophils.
  • Platelet Count: The number of platelets in the blood, which help the blood to clot.

Test Procedure

To perform a CBC, a healthcare professional will:

  • Collect a blood sample from a vein in the arm or finger
  • Use a needle and syringe or a lancet to collect the blood sample
  • Send the blood sample to a laboratory for analysis

Results

The results of a CBC are typically reported as follows:

  • Normal Range: The expected range of values for each component measured.
  • Abnormal Results: Values that fall outside the normal range, which may indicate an underlying medical condition.

Interpretation

The interpretation of CBC results depends on various factors, including:

  • Age and sex of the individual
  • Medical history and current health status
  • Presence of underlying medical conditions
  • Medications or treatments being taken

Clinical Significance

A CBC is a valuable diagnostic tool that can help healthcare professionals:

  • Diagnose and monitor blood disorders, such as anemia, leukemia, and lymphoma
  • Evaluate the effectiveness of treatments for blood disorders
  • Screen for underlying medical conditions, such as infections, inflammation, and immune system disorders

Article last updated on: 6th June 2025.
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