What is the purpose of the WBC differential test?

The purpose of the WBC (white blood cell) differential test is to assess the various types of white blood cells present in a sample of blood. This test provides valuable insights into a person's immune system status and can help identify infections, allergies, and various diseases. Each type of white blood cell plays a unique role in the immune response, and understanding the proportions of these cells can help healthcare providers diagnose conditions such as bacterial or viral infections, inflammatory diseases, and hematologic disorders. This differentiation is important because a change in one type of white blood cell can indicate specific health issues, allowing for timely and appropriate medical intervention.

The other options focus on different aspects of blood and body function that are not relevant to the WBC differential. Hemoglobin levels are evaluated through a separate test known as a complete blood count (CBC) but do not provide information about white blood cell types. Blood type determination involves testing for specific antigens on the surface of red blood cells, which is unrelated to white blood cell analysis. Evaluating kidney function typically involves tests such as creatinine levels or urinalysis, further distancing it from the purpose of a WBC differential.