Correlation of Salivary Uric Acid and Cardiac Autonomic Modulation in Metabolic Syndrome Population

Uric acid, the final metabolic product resulting from purine degradation, contributes significant quantity of the antioxidant capacity that exists in blood and saliva. As there exist a linear relationship between serum and salivary uric acid levels, estimating salivary uric acid level (SUA) instead of serum uric acid level itself is enough to serve the purpose. Aim of the study was to compare salivary uric acid level with the severity of metabolic syndrome and to correlate it with the cardiac autonomic modulation. Measurement of salivary uric acid was done with semi-automated biochemical analyzer by enzymatic colorimetric method. The ECG was recorded by using limb lead II and the signal obtained was analyzed by using HRV analysis software version 1.1. (Biomedical Signal Analysis Group, Department of Applied Physics, University of Kuopio, Finland). Time-domain parameters like mean RR interval (p<0.001), NN50 (p = 0.027) and pNN50 (p = 0.02) showed significant negative correlation with salivary uric acid. Pearson’s correlation analysis of salivary uric acid showed a significant positive correlation with frequency-domain parameters like LF (r = 0.282, p<0.001) and LF/HF (r = 0.475, p<0.001) and showed a significant negative correlation (r = -0.258, p<0.001) with HF. Salivary uric acid measurement is a non-invasive, less time-consuming and also cheap, it can be used to screen metabolic syndrome and its components thereby reducing the cardiovascular disease burden too. The HRV parameters which showed correlation with SUA also indicated increased sympathetic activity and thus may be used along with SUA to assess the severity of both MS and CVD.