Evaluation of conductivity‐based osmolality measurement in urine using the Sysmex UF5000. Issue 1 (24th September 2020)

• Record Type: Journal Article
• Authors: Yoo, Dong‐Won; Lee, Sun Min; Moon, Soo Young; Kim, In‐Suk; Chang, Chulhun L.
• Is Part Of: Journal of clinical laboratory analysis. Volume 35:Issue 1(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-09-24
• Subjects: automated urine analyzer -- comparison -- conductivity -- OsmoPro -- UF5000 -- urine osmolality; Diagnosis, Laboratory -- Periodicals; Medical laboratory technology -- Periodicals; 616
• DOI: 10.1002/jcla.23586
• Languages: English
• ISSNs: 0887-8013

Abstract

Abstract: Background: Automated flow cytometry‐based urine analyzer is increasingly being used to identify and enumerate cells and particles in urine specimens. It measures electrical conductivity which could be transformed to osmolality. Using this machine, all urine specimens could be screened for osmolality without requiring a separate dedicated device. We evaluated the performance of the new instrument, the UF‐5000 (Sysmex Corporation), in the measurement of urine osmolality. Methods: The precision of urine osmolality measurement by the UF‐5000 was evaluated for 20 days and 4 times a day for 2 concentrations. The linearity and detection capability were evaluated according to the Clinical and Laboratory Standards Institute guidelines. For comparison, 270 random urine specimens from patients were tested simultaneously using the UF5000 and the OsmoPro micro‐osmometer (Advanced instruments). Results: The laboratory‐based coefficient variations were less than 5%. Urine osmolality using the UF‐5000 has a verified linear range (y = 1.097x + 16.91, R 2 = .997). Within the comparison analysis, the mean difference was not large (−7.72%) but each differences were largely dispersed with 95% limits of agreement (LoA) from −70.5 to 55.06%, and the mean absolute difference −28.3 mOsm/kg with 95% LoA from −295.13 to 238.45 mOsm/kg. Cohen's kappa value was 0.54 (95% CI, 0.45‐0.63). Conclusions: The UF‐5000 measured conductivity and generated an acceptable quantitative analysis of urine osmolality. When compared with the results of the freezing point depression method used by the OsmoPro, a percentage of the measured urine osmolality by the UF‐5000 was outside the allowable limit. Abstract : Passing‐Bablok regression plot comparing conductivity method UF‐5000 to freezing point osmometer, OsmoPro. The continuous line represents the equality line, and the dotted lines represent allowable difference ± 28.3% interval.