Salivary markers of kidney function — Potentials and limitations

•Saliva is an interesting diagnostic fluid with easy and non-invasive collection.•Creatinine and urea can be reliably measured in saliva.•Other markers of renal functions are detectable in saliva.•Patients with chronic kidney diseases can benefit from saliva monitoring.

Saliva can be collected non-invasively, repeatedly and without trained personnel. It is a promising diagnostic body fluid with clinical use in endocrinology and dentistry. For decades, it is known that saliva contains also urea, creatinine and other markers of renal function. Clinical studies have shown that the salivary concentrations of these markers could be useful for the assessment of kidney function without the need of blood collection. This article summarizes the clinical and experimental data on the use of saliva as a diagnostic fluid in nephrology and points out the advantages, pitfalls, technical requirements and future perspective for the use of saliva as a novel potential diagnostic biofluid.