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3-part versus 5-part hematology systems

3-part versus 5-part hematology systems

A complete blood count (CBC) is typically the first test requested by a physician to evaluate a patient’s general health status. For such screenings, automated hematology analyzes are frequently used. In addition to determine blood levels of platelets (PLT), red blood cells (RBC), and white blood cells (WBC), most analyzer can also differentiate WBCs into 3 (LYM, MID, GRAN) or 5 (LYM, MONO, NEU, EOS, BASO) subpopulations. Although a so called 3-part hematology analyzer provides sufficient information for most clinical settings, trends show an increased interest in 5-part instruments. While 5-part analyzers can offer more detailed information on the white blood cells, 3-part instruments can offer great cost benefits.

Clinical settings where 3-part differentials and 5-part differential can provide different advantages

Although each WCB type provides information that helps diagnose blood-related conditions, a 3-part instrument will provide sufficient information for the typical physician office laboratory (POL). With a simple CBC, the neutrophil and lymphocyte counts will answer the question of a viral infection or a bacterial infection that can be treated with antibiotics (Fig 1).


Figure 1. Test result from a 3-part hematology analyzer visualized in a histogram.

For specialty laboratories, however, a 5-part instrument can provide a more detailed and targeted assessment of the blood status. To distinguish eosinophils and basophils from neutrophils, for example, a 5-part differentiation is mandatory (Fig 2).


Figure 2. Test results from a 5-part hematology analyzer are visualized in a 4-part differential scattergram and a separate scattergram for BASO. Ghost = nucleated RBC, lyse-resistant RBC, and platelet clumps.

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