Saliva as a non-invasive biomarker for chronic kidney disease: Challenges and potential in disease monitoring

Chronic kidney disease (CKD) is a degenerative disorder that affects millions of people throughout the world, causing considerable morbidity and healthcare burden. Frequent blood sampling is the current gold standard for monitoring CKD to evaluate biochemical and mineral indicators. However, there are drawbacks to frequent blood draws, such as pain for patients, the possibility of infection, and higher medical expenses. Saliva-based diagnostics offer advantages such as ease of collection, reduced invasiveness, and improved patient compliance. A comprehensive literature review was conducted to analyze studies evaluating the diagnostic utility of salivary creatinine, urea, calcium, and parathyroid hormone (PTH) in patients with CKD. Various saliva collection methods, including stimulated and unstimulated approaches, were investigated for efficiency and reliability, and a correlation was shown between serum and salivary creatinine, urea, PTH, and calcium levels, indicating their potential as CKD biomarkers. Despite these promising findings, challenges such as standardization of collection methods, variability in salivary flow rates, and predictive value in association with blood parameters are addressed to ensure clinical applicability. This review explores the potential and challenges of saliva as a non-invasive alternative for CKD diagnostics.