Analytical Validation of Routine Chemistry Analytes in Miscellaneous Body Fluids Using the Beckman Coulter AU5800 Analyser: An Experimental Study

Introduction: Fluids are not routinely validated by the company’s manufacturers as a routine process, highlighting the need for laboratory physicians to establish a protocol and research the performance characteristics of analytes in bodily fluids in order to provide more accurate and precise results for improving the standard of patient care. Aim: To validate the adaptation of serum kits of the Beckman Coulter system for use in pleural, ascitic and Jackson-Pratt (JP) drain fluids for common routine chemistry analytes. Materials and Methods: This experimental study was conducted in the Department of Biochemistry, Asian Institute of Gastroenterology (AIG) Hospitals, Hyderabad, Telangana, India. The samples were collected in December 2024 for a period of seven days from December 3rd 2024, to December 10th 2024. A sample size of about 20 fluid samples was collected over the course of seven days (one week), as per Clinical and Laboratory Standards Institute (CLSI) guidelines. Accuracy, precision, linearity and carry-over studies were carried out for nine parameters in ascitic, pleural and JP drain fluids. Results: Accuracy studies showed recovery rates of 98.2- 100.2%, against Beckman Coulter serum certified reference material, consistent with expected values, and interlaboratory comparisons indicated acceptable bias. Linearity demonstrated strong correlation (r=0.98-1.0) in 20 samples for each fluid that is in ascitic, pleural, and JP drain fluids, across all analytes, confirming reliability at higher concentrations. Precision analysis (intra-day and inter-assay) revealed CV% consistently below 5%, with pleural and ascitic fluids showing excellent reproducibility. Carry-over for all nine analytes in 20 samples for each fluid (pleural, ascitic and JP drain) showed acceptable error limit that is not more than three standard deviation as well as carry-over that is within 1% of the high sample concentration. Total protein (0.02) and albumin (0.00) in pleural fluid and Amylase (0.06) in ascitic fluid showed excellent carry-over across all parameters. Conclusion: Validation of serum chemistry assays for body fluids is essential to ensure reliable laboratory reporting, as these specimens are not routinely validated by manufacturers. The present study demonstrated satisfactory analytical performance for common chemistry analytes in pleural, ascitic, and JP drain fluids using the Beckman Coulter system. Implementing standardised in-house validation protocols can improve result accuracy, enhance confidence in clinical interpretation, and contribute to better patient care.