Academy of Diagnostics & Laboratory Medicine - Scientific Short
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In assessing a patient for inflammation (chronic or acute) commonly these laboratory values are used separately or in combination: white cell counts (WBC), erythrocyte sedimentation Rate (ESR), C-reactive protein (CRP), lymphocyte absolute counts, and lactic acid. In the emergency setting there are efforts to eliminate ESR as it requires additional instrumentation and is not a specific marker of acute inflammation. 1, 2
Currently every chemistry platform can perform a CRP while an ESR requires a separate instrument just for that test alone, therefore it is time to determine if ESR testing in acute care spaces is appropriate. Yes, ESR instrumentation offers automation of a labor-intensive test method, but it increases the test menu complexity, and depending on the instrumentation, increases specimen volume. In the wake of some recent study results, offering ESR rapidly does not aid in the CRP ability to assess acute inflammation, and many facilities are removing this from an acute care test menus. 3-5
Small acute facilities, like free standing emergency departments and critical access hospitals, are required to maximize their in-house testing menus to triage and/or treat acute injuries. In these spaces the laboratory staffing may be single testing personnel per shift. To evaluate these laboratory’s test menus, each piece of instrumentation and test offering should be assessed for automation, turn-around-time, space, and clinical utility. A hematology analyzer is essential as it will provide a hemoglobin/hematocrit and a platelet count to assess bleeding and clotting hemostasis within in minutes. Along with a hematology analyzer, blood gas, chemistry, immunoassay, or urinalysis instrumentation become next on the essential testing list. And finally, those platforms that offer one or two tests need to be assessed for the criticality of testing, e.g. molecular pathogen testing, ESR instrumentation. In staffing-restricted spaces, the number of tests performed per hour as well as the complexity of that testing make-up needs to be reasonable for one individual to accomplish, to allow for successful clinical relationships. Keeping test menus feasible for the staff also leads to less burn-out and improved staff retention.
Since 2014, with the implementation of “Choosing Wisely” there have been efforts to eliminate ESR testing in assessing acute inflammation. 1 CRP rises quickly (within 4-6 hour) and will peak 36-50 hours after the onset of inflammation allowing for an initial test or serial testing to rule in an underlying inflammatory process.2 CRP is an acute phase marker produced by the liver in the inflammatory cytokine response, while ESR is non-specific physical outcome from the interaction of RBC and serum proteins and its kinetics are delayed in comparison to CRP.2 ESR can be affected by RBC abnormalities, other serum protein concentrations (fibrinogen, globulins, and albumin). ESR has been shown to add to CRP sensitivity in some clinical cases outside of acute inflammation, like connective tissue diseases or rheumatoid arthritis. This utility means that larger institutions may still find clinical usefulness for ESR. As the literature around reducing ESR testing has grown in the last decade, it may be time to remove this testing from acute care laboratory environments especially in locations where testing personnel resources are strained. 3-5
As small acute care locations continue to offer clinical care to the underserved, e.g. rural populations, there is a constant right sizing of their in-house laboratory test menu. As the last few years has come to highlight the need for rapid respiratory pathogen testing, it is probably past time to assess ESR testing and whether it should remain within the acute care space.
