Validation of the salivary urea and creatinine tests as screening methods of chronic kidney disease in Vietnamese patients

Abstract

Both salivary urea and creatinine have a high capacity for serum creatinine estimation. Salivary urea and creatinine tests can be used as low-cost, easily accessible and noninvasive tools for screening, diagnosing, monitoring treatment outcomes and ascertaining prognosis of chronic kidney disease.

Measurement of urea and creatinine in saliva of dogs: a pilot study

“…Our study showed that salivary urea and creatinine concentrations were significantly higher in CKD dogs compared with healthy subjects. These results are in agreement with previous studies made in humans where high values of salivary urea and creatinine were observed in patients with CKD [11,17,18]. An explanation for these findings is that in CKD the kidneys can not excrete creatinine and urea, and therefore their blood concentrations increase leading to the diffusion of these compounds to saliva [19].…”

Salivary levels of phosphorus and urea as indices of their plasma levels in nephropathic patients

“…Regardless of the mechanism(s) accounting for the abundance of phosphorus in saliva, the evidence of a correlation between saliva phosphorus and plasma phosphorus could be explained hypothesizing that plasma phosphorus controls the secretion and/or the diffusion of phosphorus in saliva. With regard to urea, its saliva concentrations were almost identical and highly correlated with plasma urea in accordance with previous observations . The high‐order correlation of saliva urea with plasma urea and the identity of urea concentrations in plasma and saliva reasonably reflected the chemical characteristics of urea, that is, extremely soluble and diffusive.…”

“…An important prerequisite for the use of saliva in diagnostic workup is that the salivary levels of the marker associated with a given disorder should mirror the profile of the marker in biological samples used as gold standard in medical practice. Previous observations indicated that correlations between plasma concentrations and saliva concentrations are detectable for some but not for all analytes . It is well established that small molecules as phosphorus and urea are measurable in saliva .…”

“…The use of saliva for laboratory tests has been investigated in various medical areas because saliva could be used as a noninvasive diagnostic tool . An important prerequisite for the use of saliva in diagnostic workup is that the salivary levels of the marker associated with a given disorder should mirror the profile of the marker in biological samples used as gold standard in medical practice.…”

“…As part of a project about the use of saliva tests in space medicine, this study investigated methodological aspects in saliva measurements (duplicate samples, saliva from different sites of collection, day‐to‐day variability, time of collection, effects of freezing/thawing) and correlations between plasma concentrations and saliva concentrations. Methodological aspects were investigated in healthy volunteers, whereas plasma‐saliva correlations were investigated in patients with kidney disease because low kidney function increases the levels of phosphorus and urea not only in plasma but also in saliva …”