B-058 Evaluating the analytical performance of the OsmoPRO® MAX Automated Osmometer

Abstract

Background Accurate and timely serum, plasma, and urine osmolality measurements are crucial for diagnosing and treating conditions such as hyponatremia, toxic alcohol ingestion, and diabetes insipidus. Most clinical osmometers rely on manual methods which require pipetting and testing one sample, control, or calibration standard at a time. These manual steps are time-consuming and increase the risk of human error. A new osmometer, the OsmoPRO® MAX, saves time and reduces these risks by automating freezing-point depression measurements (Advanced Instruments, LLC). The purpose of this study was to evaluate the analytical performance of the OsmoPRO MAX in measuring the osmolality of serum, plasma, and urine. Methods OsmoPRO MAX analytical performance was evaluated at Boston Medical Center in Boston, Massachusetts using four criteria: (1) Linearity was assessed with an allowable systematic error of <2 mOsm/kg H2O and an allowable total error of <6.0 mOsm/kg H2O over a range of 0-2000 mOsm/kg H2O using an Osmolality Linearity Set. (2) Simple Accuracy was evaluated over a range of 240 to 800 mOsm/kg H2O using Clinitrol™ 290 with an acceptable range of +/- 4 mOsm/kg H2O as well as Protinol™ 240, 280, and 320, each with an acceptable range of +/- 7 mOsm/kg H2O, and Renol™ 300 and 800, both with an acceptable range of +/- 10 mOsm/kg H2O. (3) Simple Precision was measured using Clinitrol 290 with an acceptable within-run standard deviation (SD) of <2.0 mOsm/kg H2O as well as Protinol 240, 280, and 320, each with an acceptable within-run SD of <3 mOsm/kg H2O, and Renol 300 and 800, with an acceptable within-run SD of <3 mOsm/kg H2O and <4.7 mOsm/kg H2O, respectively. (4) Alternative Method Comparison was conducted against the OsmoPRO® Multi-Sample Micro-Osmometer on 80 patient samples analyzed by Passing-Bablok regression analysis. Results OsmoPRO MAX passed all criteria. Linearity testing produced a negligible observable error of 0.1 mOsm/kg H2O, accurate within the allowable systematic error and all results were accurate within the total allowable error. Simple Accuracy testing produced replicates all within their specified target range. Simple Precision testing of all replicates for each standard tested fell within their respective within-run SD. Alternative Quantitative Method Comparison demonstrated strong agreement between the two methods with a correlation coefficient of 0.9998 and a bias of -2.1 (-0.6%). Conclusion This study demonstrates that the OsmoPRO MAX Automated Osmometer meets all acceptance criteria for analytical performance including linearity, simple accuracy, simple precision, and alternative quantitative method comparison against the OsmoPRO Multi-Sample Micro-Osmometer.