Serum markers of chronic dehydration are associated with saliva spinability

Findings of a relationship between saliva and dehydration have been observed, but the precise nature of these relationships is unclear and no evidence of a direct link has been found. In particular, no study reports a relationship between chronic dehydration and saliva conditions in community-dwelling older adults. This study aimed to identify whether salivary conditions are sensitive to body hydration markers in an elderly population. A total of 403 subjects aged 76 years participated in the study. Stimulated saliva flow rate and spinability of saliva were measured. In addition, determinations of serum levels of uric acid, blood urea nitrogen (BUN), creatinine, sodium and potassium were made. Dehydration was defined as uric acid >/= 7 mg dL(-1) according to the standard value. The salivary spinability were significantly associated with the concentration of uric acid (OR=2.06, P=0.044) according to multiple logistic regression analysis. In addition, after adjusting for gender, the uric acid concentration and the salivary spinability was significantly associated with BUN, potassium and creatinine levels. The subjects with high uric acid levels (>/= 7 mg dL(-1)) had the most elastic saliva. Both BUN and serum creatinine are the most commonly used indicators of renal function. Therefore, our findings might demonstrate that older adults who are dehydrated showed highly elastic saliva, which was associated with renal function. In conclusion, this study suggests that there is a significant relationship between chronic dehydration status and salivary spinability level.