Aziz Şener, Serhat Takil, Arzu Kösem
Academic Journal of Health - 2025;3(3):94-97
Objective Lactate is an early biochemical marker of tissue hypoxia and hypoperfusion and plays an important role in clinical decision-making. This study aimed to compare lactate measurements obtained from blood gas and central laboratory biochemistry analyzers in pediatric patients and to evaluate the clinical agreement between the two methods. Methods Pediatric patients with simultaneous lactate measurements performed on blood gas and biochemistry analyzers at the Ankara Etlik City Hospital Medical Biochemistry Laboratory between January 2023 and August 2025 were retrospectively reviewed. A total of 914 paired lactate measurements were included. Method comparison was performed using Pearson correlation, Bland-Altman analysis, Passing-Bablok regression, and Cohen's kappa coefficient. A total allowable error (TEa) of +/-0.20 mmol/L was used as the clinical acceptance criterion. Results A very strong positive correlation was observed between blood gas and biochemistry measurements (r = 0.95, p < 0.0001). Bland-Altman analysis showed a mean bias of -0.13 mmol/L (95% CI: -0.18 to -0.08), with limits of agreement (LoA) from -1.56 to 1.31 mmol/L; 95.1% of results fell within these limits. Passing-Bablok regression yielded y = 0.211 + 0.975x (intercept 0.211, 95% CI: 0.168-0.251; slope 0.975, 95% CI: 0.954-0.996), with no deviation from linearity (CUSUM p = 0.97). Categorical agreement was substantial (kappa = 0.73, 95% CI: 0.70-0.76), and misclassification remained below 10%. Conclusion Blood gas and biochemistry analyzers demonstrated a high level of agreement for lactate measurement in pediatric patients. The rapid turnaround time of blood gas analyzers may support timely clinical decision-making, particularly in emergency and intensive care settings. Although minor differences were observed at low and high concentrations, these were not large enough to meaningfully affect clinical interpretation.
