Three Neglected Numbers in the CBC: the RDW, MPV, and NRBC Count
REVIEW JORI E. MAY, MD MARISA B. MARQUES, MD VISHNU V.B. REDDY, MD RADHIKA GANGARAJU, MD Department of Medicine, Department of Pathology, Department of Pathology, Department of Medicine, University of University of Alabama, University of Alabama, Birmingham University of Alabama, Birmingham Alabama, Birmingham Birmingham Three neglected numbers in the CBC: The RDW, MPV, and NRBC count ABSTRACT he complete blood cell count (CBC) T is one of the most frequently ordered lab- The complete blood cell count (CBC) is one of the most oratory tests in both the inpatient and outpa- frequently ordered laboratory tests, but some values tient settings. Not long ago, the CBC required included in the test may be overlooked. This brief re- peering through a microscope and counting view discusses 3 potentially underutilized components the red blood cells, white blood cells, and of the CBC: the red blood cell distribution width (RDW), platelets. These 3 numbers are still the primary the mean platelet volume (MPV), and the nucleated purpose of the test. red blood cell (NRBC) count. These results have unique Now, with automated counters, the CBC diagnostic applications and prognostic implications that report also contains other numbers that delin- can be incorporated into clinical practice. By understand- eate characteristics of each cell type. For ex- ing all components of the CBC, providers can learn more ample: about the patient’s condition. The mean corpuscular volume is the aver- age volume of red blood cells. Providers use it KEY POINTS to classify anemia as either microcytic, normo- The RDW can help differentiate the cause of anemia: eg, cytic, or macrocytic, each with its own differ- a high RDW suggests iron-defi ciency anemia, while a nor- ential diagnosis.
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