What is a complete blood count (CBC) primarily used for?

A complete blood count (CBC) is primarily used for evaluating overall health and detecting various disorders. This test provides critical information about the components of blood, including red blood cells, white blood cells, hemoglobin, hematocrit, and platelets. By analyzing these elements, healthcare providers can identify a wide range of conditions, such as anemia, infections, inflammation, and certain blood disorders.

The comprehensive nature of the CBC makes it an essential diagnostic tool in routine health screenings and evaluations when patients present with symptoms impacting their overall health. This is why option B is the most accurate description of the primary use of a CBC.

The other options focus on specific areas of health monitoring. Assessing blood electrolyte levels and monitoring kidney function, while important, are more specific tests that don't provide the broad range of information that a CBC does. Diagnosing liver diseases typically relies on liver function tests rather than a CBC. Thus, while all these tests have their specific uses in medical evaluation, the CBC stands out for its role in providing a snapshot of a patient's overall health and helping detect a variety of conditions.