Background: Chronic kidney disease (CKD) is a growing global health challenge characterized by metabolic alterations, particularly elevated serum urea and creatinine levels, requiring repeated blood investigations. Saliva, as a non-invasive and easily accessible bio-fluid, may serve as an alternative to serum for biochemical assessment. This study aimed to compare salivary and serum creatinine and urea levels in CKD patients and to evaluate the diagnostic utility of salivary biomarkers. Materials and Methods: This cross-sectional study included 70 participants, 35 patients with chronic renal disease and 35 age and sex-matched healthy controls. Blood and unstimulated saliva samples were collected and centrifuged. Creatinine and urea levels in both serum and saliva were measured with an automated analyser. Group comparisons were performed using Student’s t -test. Correlation between serum and salivary parameters was assessed using Spearman’s rho correlation. Diagnostic accuracy was assessed using receiver operating characteristic (ROC) curve analysis. Results: Serum and salivary creatinine and urea levels were significantly higher in CKD patients compared to controls. A positive correlation was observed between serum and salivary creatinine and urea levels. The area under the ROC curve was 0.702 for salivary creatinine and 0.922 for salivary urea. The optimal cut-off values were 0.45 mg/dl for salivary creatinine and 45 mg/dl for salivary urea with sensitivities of 82.9% and 91.4% and specificities of 45.7% and 65.7%, respectively. Conclusion: Salivary creatinine and urea levels correlate significantly with serum levels in CKD patients. Saliva may serve as a non-invasive alternative for renal function assessment, with salivary urea demonstrating higher diagnostic accuracy.
Sankari et al. (Thu,) studied this question.