It’s been called “the refuge of the intellectually destitute (physician)” by Amal Muttu. The CBC is a much maligned test that is nevertheless one of the the most frequently ordered diagnostic tests in the ED. To truly know how to interpret this test, one must understand its individual components, the possible causes of variations from normal for those components, and how it integrates into the clinical presentation of the patient. Also, it can’t help but to know and understand some of the historical background…