Quick Guide: Complete blood cell count (CBC) Blood Test
What it is: A complete blood count (CBC) measures the amounts and sizes of red blood cells, white blood cells, hemoglobin, and platelets in a blood sample; a CBC "with differential" also breaks down the different types of white blood cells.
Why it's ordered: Ordered as routine health screening or to help diagnose and monitor conditions like anemia, infection, inflammation, bleeding disorders, or blood cancers.
What it detects: Abnormal red blood cell counts can indicate anemia or polycythemia; abnormal white blood cell counts or differential can indicate infection, inflammation, allergic reactions, or leukemia; abnormal platelet counts can indicate bleeding or clotting disorders.
Collection & prep: A standard blood draw from a vein in the arm. No special preparation is typically required.
Results:
Abnormal red cell values – may suggest anemia or a red blood cell overproduction disorder
Abnormal white cell values – may suggest infection, inflammation, or a blood cancer, depending on which cell type is affected
Abnormal platelet count – may suggest a bleeding or clotting risk
Possible complications: A CBC is a screening tool rather than a diagnosis — abnormal results typically prompt a peripheral blood smear or further targeted testing (like iron studies or bone marrow evaluation) to identify the specific cause.
Statements made in the Clinical Manual have not been evaluated by the FDA. The products mentioned are not intended to diagnose, treat, cure or prevent any disease.
