Salivary Creatinine Assays as a Potential Screen for Renal Disease

Abstract

SUMMARY. Salivary creatinine concentrations are 10-15% of serum creatmme concentrations in healthy populations but have not previously been measured in patients with renal disease. The Cobas Mira automated Jaffe method was adapted to measure salivary creatinine concentration. The method was linear to 1200/lmol/L, had a mean recovery of 78% and a detection limit of 6/lmol/L. Intra-assay variability was 13·5, 5·5 and 1·4% at 10'6, 17·8 and 128·4/lmo1/L, respectively. Interassay variability was 35·0 and 4·8% at 6·2 and 130·4/lmol/L, respectively. The median salivary creatinine concentrations was 8·5 /lmo1/L (range 6-18/lmol/L) in healthy subjects (n=23), and 84/lmo1/L (range 18-591 /lmol/L) in patients with renal disease (n = 25). Salivary and serum creatinine concentrations were not related in healthy subjects, however, a significant relationship was found in the patients (r = 0'784, P< 0·001). Using salivary creatinine concentration of 16·8 /lmol/L as a cut off value, all patients would have been detected with one false positive result (sensitivity 100%, specificity 95·7%, efficiency 97'7%). Thus, salivary creatinine estimations may be used to identify subjects with serum creatinine concentrations above 120/lmol/L.

Salivary Creatinine Estimation as an Alternative to Serum Creatinine in Chronic Kidney Disease Patients

“…But in contrast to our study, Xia et al [18] found a positive correlation in both their cases ( r = 0.971) and controls ( r = 0.932) while we obtained a positive correlation only in CKD patients similar to Lloyd et al [21]. …”

Realising the Potential of Urine and Saliva as Diagnostic Tools in Sport and Exercise Medicine

“…It is primarily composed of water, with an abundance of weak and strong ions, where their concentration is dependent on secretion stimulation type [67]. Organic non-protein compounds such as uric acid, creatinine, bilirubin, glucose, amino acids, fatty acids, amines, and lactate are also detectable [59,[68][69][70][71][72][73]. Other constituents include up to 2290 proteins [74], comprised mainly of amylase, sIgA, carbonic anhydrase, and prolinerich proteins, catecholamines [75], and hormones such as cortisol and testosterone, whose concentrations represent serum-free levels [76].…”

Saliva as a diagnostic fluid

“…However, there are some. For example, salivary creatinine concentrations show a high sensitivity and specificity for determining the presence of renal disease (Lloyd, Broughton and Selby, 1996). Much more research is required before any role for saliva‐based diagnosis can be assigned in nephrology.…”