Role of Saliva as an Alternate Body Fluid in Evaluation of Kidney Function.

Chronic Kidney Disease (CKD) is a condition, where the kidneys deviate from their normal physiology particularly excretion and regulatory function. There are many researches being performed on the development of rapid, effective and accurate diagnostic methods. The potential role of saliva has invited the attention in diagnostics as it is a non invasive, easy to collect and more economical as compared to traditional sampling methods. Recent studies emphasized that the saliva has been considered as an alternative diagnostic fluid sample and has been used to diagnose various autoimmune diseases, diabetes, cardiovascular diseases, dental caries and other oral diseases. Material: This cross-sectional study was done on 150 subjects involving 75 CKD - stage 4 & 5 (KDIGO 2012 CRITERIA) and 75 age and sex matched healthy controls. After collection of saliva and blood samples, urea was analysed by enzymatic calorimetric method and creatinine by modified Jaffes's method. Data was expressed as Mean ± SD. Comparison and correlation between groups were done by Mann-Whitney U test and Spearman's correlation method respectively and p-value <0.05 was considered to be statistically significant. Observation: The mean and Standard Deviation (S.D.) of serum creatinine, urea and salivary creatinine, urea are 6.94 ± 3.1, 110.8 ± 43.1 and 0.8 ± 0.7, 130 ± 51.9 respectively. Levels of creatinine and urea were higher in saliva in CKD patients compared to controls as also observed in serum. We observed a Positive correlation between serum and salivary creatinine (Correlation Coefficient 0.94) and urea (Correlation Coefficient 0.52) with p value <0.001. Linear regression analysis of Serum and Salivary Creatinine of CKD patients was significant. Using regression equation eGFR values calculated from salivary creatinine showed good agreement with measured serum creatinine.