Abstract
Introduction. The utility of salivary bicarbonate as a non-invasive marker of systemic acid-base status in pediatric patients remains unclear. This study investigated the possible correlation between salivary and blood gas analysis at risk for acid-base disturbances, including those with chronic kidney disease (CKD) or receiving acetazolamide.
Methods. In a single-center cross-sectional study (July 2024–March 2025), 94 pediatric patients (6–18 years) underwent simultaneous blood and saliva sampling for gas analysis. Patients were stratified into metabolic acidosis (<22 mmol/L), normal (22–26 mmol/L), or metabolic alkalosis (>26 mmol/L) groups based on serum bicarbonate.
Results. No relationship was observed between salivary and serum bicarbonate (r = 0.112, p = 0.281), pH, or base excess. However, strong correlations emerged within salivary parameters: bicarbonate was positively associated with salivary pH (r = 0.682, p < 0.001) and base excess (r = 0.865, p < 0.001). Patients with eGFR <30 ml/min/1.73m² had significantly higher salivary bicarbonate (13.6 mmol/L vs 6.8 mmol/L, p = 0.004), independently of bicarbonate supplementation. This was also negatively associated with calcium (β = –8.67, p = 0.004) and lactate (β = –0.82, p = 0.008). Dialysis status and underlying diagnosis were additional independent predictors. While patients with metabolic acidosis showed higher median salivary bicarbonate than those with normal or alkalotic profiles, this difference was not statistically significant (p = 0.545).
Conclusions. Salivary bicarbonate does not reflect systemic acid-base balance but is elevated in advanced CKD, suggesting a local regulatory phenomenon worthy of further exploration.
Keywords: saliva, acid-base equilibrium, chronic renal insufficiency, child, noninvasive diagnostic techniques





