Correlation between salivary and serum biomarkers of kidney function in chronic kidney disease patients attending the nephrology clinics at Teaching Hospital Karapitiya, Sri Lanka

The present study was designed to determine the correlation between salivary and serum levels of creatinine and urea in patients with chronic kidney disease (CKD) and to propose the use of saliva as an alternative medium for the analysis of biochemical parameters of kidney function. Accordingly, an analytical cross-sectional study was carried out using 100 CKD patients attending the Nephrology Clinics at Teaching Hospital Karapitiya, Sri Lanka. Saliva and serum samples were collected from the patients for the estimation of creatinine and urea using spectrophotometric assay kits. Of the total, the majority of the patients were found within CKD stage 3 (82%). The salivary and serum concentrations of creatinine varied within the range of 0.20 - 2.10 mg/dL and 1.54 – 11.6 mg/dL, whereas the salivary and serum concentrations of urea varied within the range of 68.04 – 127.59 mg/dL and 60.14 – 168.25 mg/dL respectively within the study population. Significant positive correlations were observed between the salivary and serum concentrations of creatinine (r= 0.985, p=0.01), and urea (r= 0.942, p=0.01), and between salivary concentrations of creatinine and urea (r=0.887, p=0.01). A significant difference was observed in the salivary biomarkers between mild to moderate stages of CKD patients and severe to end-stage CKD patients. No significant association was observed in the salivary markers with the age and sex of the patients. The area under curve values in the receiver operating characteristic analysis was>0.9 (95% CI). These findings revealed high levels of diagnostic accuracy in salivary biomarkers suggesting the potential use of saliva for the assessment of kidney function in CKD patients.