Salivary Uric Acid a Valid Biomarker for Wide Range of Conditions, Including Huntington’s, Study Finds

Salivary uric acid is a valid biomarker for a wide range of potential conditions and disease states, including Huntington’s disease, according to a recent study.

The study, “The validity, stability, and utility of measuring uric acid in saliva,” was published in the journal Biomarkers in Medicine.

Technical advances have allowed researchers to measure a broad spectrum of biomarkers that can be used for diagnosis, prognosis and measuring the effectiveness of treatments.

Uric acid is a breakdown product of purine nucleotides — the basic building blocks of DNA — and has been used as a biomarker.

“In humans, uric acid is one of the most potent and most prevalent anti-oxidants in the blood, contributing over half the antioxidant capacity of blood plasma,” Steve Granger, PhD, chief strategy officer of Salimetrics, said in a press release.

High levels of uric acid, known as hyperuricemia, have been associated with hypertension (high blood pressure), stroke, and chronic kidney disease, as well as a higher risk for metabolic syndrome, insulin-resistance, obesity, and Type 2 diabetes.

Studies have also linked high levels of serum uric acid to beneficial outcomes in neurodegenerative disorders such as age-related mild cognitive impairment, Alzheimer’s, Parkinson’s, and Huntington’s diseases.  

Given uric acid’s association with a wide spectrum of conditions, disorders, and health behaviors, a noninvasive method to measure its levels would be particularly useful in clinical research and could increase participation in screening, monitoring, and treatment programs.

Studies had already demonstrated that uric acid levels in the blood correlate well to those in the saliva, suggesting that salivary uric acid levels could be used as an alternative, noninvasive specimen.

To examine the validity and stability of salivary uric acid as a marker of systemic uric acid and associations between salivary uric acid and cardiovascular and metabolic biomarkers, researchers collected and examined blood serum and salivary uric acid levels from 99 healthy young adults, ages 18-36, 53 of whom were male, and analyzed the correlation between serum and saliva uric acid.

To examine the short- and long-term stability of salivary uric acid, researchers used data from a sample of 182 undergraduate student members of the Arizona State University marching band. Samples were analyzed using the Salimetrics Salivary Uric Acid Assay Kit.

The correlation between serum and saliva uric acid levels was robust, and salivary uric acid levels were relatively stable.

Next, researchers looked at the association between uric acid, adiponectin (a decrease of which is associated with cardiovascular and metabolic disorders), and C-reactive protein (an inflammatory marker).

As expected, levels of uric acid and adiponectin were inversely related, indicating that high uric acid levels corresponded with a higher risk for cardiovascular and metabolic disorders.

Neither salivary nor serum uric acid were associated with either salivary or serum C-reactive protein.

Salivary uric acid was also not correlated to inflammatory activity as measured by levels of pro-inflammatory cytokines (a type of immune molecule) in the serum and saliva.

Researchers considered this result unsurprising since study participants were young, healthy adults with good oral health and therefore did not have high inflammatory activity.

“Findings from these studies provide new insight and support for salivary [uric acid] as a valid, stable and useful index of systemic [uric acid] activity,” the researchers wrote.

“When you pair the robust performance characteristics of Salimetrics’ Salivary Uric Acid Assay with the stability of uric acid in saliva enabling the potential for at home collections, the research applications are near limitless. This is an exciting time to facilitate new discoveries,” Granger said.

“Salivary uric acid has widespread potential in biobehavioral and health research, and there is a critical need to further understand the complex biological relationships that connect uric acid with health and well-being,” said Jenna Riis, PhD, a researcher at the Institute for Interdisciplinary Salivary Bioscience Research at the University of California, Irvine.