Evaluation of acetaminophen recovery in human serum

Abstract

Background Acetaminophen toxicity can lead to hepatic and renal damage. Early and accurate measurement of acetaminophen is critical for the management of patients. The Royal College of Pathologists Quality Assurance Program (RCPA-QAP) end of cycle report for acetaminophen shows a significant negative bias (18%) when compared to the median of all values and methods. This may have serious implications for patient samples if the true values are underestimated by the same extent. The aim of this study is to evaluate whether this bias is real. Methods A series of samples was prepared using an acetaminophen spiked human serum pool diluted with non-spiked matching serum across the stated measurement range and measured on the Roche Modular PPE by enzymatic assay. Recoveries were calculated and the values at the decision points for hepatic and renal toxicity were evaluated (200–1300 µmol/L). Results Ten levels of acetaminophen were examined. The bias across the concentration range was Conclusion The negative bias evident from EQAP measurements is absent when tested in human serum pools. This indicates that acetaminophen is accurately measured in the Modular PPE and is fit for purpose for monitoring of acetaminophen toxicity.