A-122 Fluid Type (STILL) Matters: An Analysis of Quality Control Material Suitability for Measuring Eleven Body Fluid Analytes in the Clinical Laboratory

Abstract

Abstract Background Measuring the concentration of albumin, amylase, bilirubin, cholesterol, creatinine, glucose, lactate dehydrogenase (LDH), lipase, total protein(TP), triglycerides, and urea nitrogen(UN) in body fluids(BFs) provides important information to aid in clinical decision-making. The range of expected values of these analytes in BFs may not match serum, and the distribution by fluid type is not well described. Quality control (QC) materials are designed to reflect clinically relevant concentrations in blood. Hence, the measuring ranges for assays modified for BF testing vary in suitability. Laboratorians and manufacturers would benefit from understanding the overlap in BF and serum analyte concentrations. The aim of this study was to characterize the range of BF analyte concentrations compared to serum and assess the suitability of QC materials used on these assays. Methods A retrospective analysis was performed for the following analytes in BFs with reportable ranges(including maximum dilution factor): albumin = 0.2–12.0 g/dL(×2), amylase = 3–14 000 U/L(×100), bilirubin = 0.1–72.2 mg/dL(×2), cholesterol = 4–8000 mg/dL(×10), creatinine = 0.1–92.0 mg/dL(×4), glucose = 2–3375 mg/dL(×5), LDH = 10–9000 U/L(×10), lipase = 3–300 000 U/L(×1000), TP = 0.2–36.0 g/dL(×3), triglycerides = 4–8850 mg/dL(×10), and UN = 2–300 mg/dL(×3). Chemistry tests were run on a cobas® 6000 c501 (Roche Diagnostics,Indiana). Patient analyte concentration and fluid type results reported between 9/16/2019 and 1/27/2022 at all Mayo Clinic locations were extracted from an institutional database of electronic medical record data. Serum results were included for comparison. Descriptive statistical analyses (median and range) were performed with R (version 4.2.2)/R Studio(version 2022.12.0). QC materials for BF testing were purchased from Bio-Rad (Multilevel Qual, Levels 1 and 3; Hercules, CA, USA). Target concentrations are reported. Results Conclusion BF median (range) concentrations are similar or higher for bilirubin, creatinine, glucose, lipase, and UN. Serum QC material is likely appropriate for these assays in BFs. BF median(range) concentrations are lower for albumin, cholesterol, TP, and triglycerides suggesting that serum QC material may not be well suited for BFs. The need for extended dilutions may impact BF amylase and lipase.