Why get tested?
To determine if red blood cells, white blood cells, and platelets are normal in appearance and number; to distinguish between different types of white blood cells and to determine their relative percentages in the blood; to help diagnose a range of deficiencies, diseases, and disorders involving blood cell production, function, and destruction; to monitor cell production and cell maturity in diseases such as leukemia, during chemo/radiation therapy, or in the evaluation for hemoglobin variants

When to get tested?
When CBC results are abnormal, a blood smear with manual WBC differential is performed to determine the presence of abnormal or immature cells; when a doctor suspects a deficiency, disease, or disorder that can affect blood cell production; when you are being treated for a disease with medications that may have an affect on blood cell production

Sample required?
A blood sample drawn from a vein in your arm or by pricking a finger, ear or, in the case of an infant, a heel