Performance Evaluation of Dry Chemical Colorimetry for Plasma Ammonia Detection on the VITROS 350 Chemistry System

OBJECTIVE: Plasma ammonia quantitation is one of the most valuable laboratory tests for assessing hepatic function. Accurate measurement is clinically imperative for the diagnosis and management of severe hepatobiliary diseases. This study aimed to comprehensively evaluate the analytical performance of the VITROS dry chemistry system with dry chemical colorimetry for plasma ammonia detection. METHODS: A full performance validation was conducted on the VITROS 350 Chemistry System in accordance with the guidelines of the Clinical and Laboratory Standards Institute (CLSI) and the China National Accreditation Service for Conformity Assessment (CNAS). Comparability was performed using the VITROS 350 Chemistry System and VITROS 5600 Integrated System across our center and four external laboratories. RESULTS: The VITROS 350 platform demonstrated robust analytical performance for plasma ammonia testing. Precision, accuracy, upper limit of the reportable interval, linearity, and carryover rates were all compliant with both clinical requirements and manufacturer specifications. Comparative analysis revealed strong inter-platform concordance, with results from five concentration levels across five laboratories remaining within predefined allowable limits. Regarding interference, only high concentrations of hemoglobin exerted a clinically significant impact on test results, a finding consistent with established clinical experience and diagnostic expectations. CONCLUSION: This study validates the reliability of the VITROS dry chemistry system for routine plasma ammonia testing. It provides clinical laboratories with a robust framework for method selection and establishes a framework for future external quality assessment (EQA) based on dry chemistry colorimetry.