Comparisons of metabolite profile from paired serum and ethylenediaminetetraacetic acid–plasma samples using dry chemistry technology: An emergency department perspective

BACKGROUND: No data is available evaluating the difference in serum versus plasma sample assay of commonly tested parameters in the emergency department, where the sample processing time can be significantly reduced if plasma is used for analysis instead of conventionally used serum. Hence, this study aimed to evaluate the differences in serum versus plasma sample estimation of commonly evaluated biochemical parameters using dry chemistry technology. MATERIALS AND METHODS: Paired blood samples were collected from a single venipuncture of 405 patients admitted to the emergency department. Dry chemistry autoanalyzer (Vitros-350, Ortho Clinical Diagnostics) was used to process all the samples. RESULTS: Data from 401 patients were analyzed. Percentage differences between serum versus plasma samples for all analytes ranged from 0.0% to 57.44% and were <±4% for a majority of parameters, except uric acid (−6.25%), albumin (+11.90%), chloride (–5.05%), phosphorus (−6.06%), creatine phosphokinase (CPK) total (−57.44%), amylase (−37.53%), lipase (−42.74%), lactate dehydrogenase (LDH) (−8.53%), and C-reactive protein (−7.44%). For albumin, CPK total, amylase, and lipase, the difference between serum and plasma samples was more than the accepted upper range recommended by College of American Pathologists. CONCLUSION: Glucose, urea, creatinine, bilirubin, total protein, serum glutamate-pyruvate transaminase, total cholesterol, high-density lipoprotein cholesterol, triglycerides, sodium, and CPK-mb can be reliably assayed from either serum or plasma samples in emergency/routine practice. CPK total, amylase, and lipase should always be assayed from serum and not plasma due to significant variations. Uric acid, chloride, phosphorous, and LDH only in emergency situations should be assayed from plasma. For routine assays, serum should be preferred.