Stability, accuracy, and clinical performance of enzymatic total CO2 measurement: Evaluation of the Snibe and Roche assays

Abstract

Objectives To evaluate the stability, accuracy, and clinical performance of the Snibe CO2 assay compared with the Roche CO2 reagent and to investigate factors affecting total CO2 measurements in different clinical conditions. Methods Total CO2 was measured in patient samples using enzymatic assays. Stability was assessed over time, and CO2 loss was examined in different blood collection tubes. Method comparison was conducted between the Snibe and the Roche CO2 assays in various diseases. Results The Snibe CO2 assay showed excellent linearity (r=0.9997) and maintained stability for 42 days without recalibration, with control material deviations within ±5% of the target. CO2 loss was observed in uncapped non-anticoagulant tubes (24.0% decline over 48 hours), but was less in EP tubes (9.4% decline). Significant differences of median CO2 measurements were observed in only the renal group (Snibe: 13.35 mmol/L, Roche: 12.80 mmol/L) and the cardiovascular disease group (Snibe: 25.90 mmol/L, Roche: 26.40 mmol/L) versus the healthy group (Snibe: 22.70 mmol/L, Roche: 22.90 mmol/L) for both the Snibe and Roche assays. Conclusions The Snibe CO2 assay demonstrated superior stability and comparable accuracy compared with the Roche reagent. Preanalytical CO2 loss remains a critical issue, emphasizing the need for standardized sample handling. Given the correlation between total CO2 and bicarbonate levels, accurate measurement is critical for diagnosing metabolic disorders. Laboratories should establish protocols to minimize errors and ensure reliable acid-base assessment in clinical practice.