What is one of the critical functions of blood drawn for a CBC?

The critical function of blood drawn for a Complete Blood Count (CBC) is primarily to monitor white blood cell function. A CBC provides key information about the different cellular components of blood, including the white blood cells (WBCs), which play a crucial role in the immune system. Analyzing the WBC count and the differential count allows healthcare providers to evaluate for the presence of infections, inflammation, and other medical conditions that may affect immune response. A CBC can show whether the white blood cells are within a normal range or altered, indicating potential health issues such as autoimmune disorders, hematologic diseases, or reactions to medications.

While hydration status, blood oxygen levels, and specific antibodies are important medical assessments, they are not primary functions assessed through a standard CBC. Hydration status might be evaluated through the concentration of certain blood components, but it is more typically assessed through methods like electrolyte tests. Blood oxygen levels are primarily determined by arterial blood gas analysis, and checking for specific antibodies usually involves different tests designed for serology rather than a routine CBC.