Is lower uric acid level better? A combined cross-sectional and longitudinal study in the elderly.

The relationship between metabolic syndrome (MetS) and uric acid (UA) has been explored in many studies, but there is paucity of information on hypo-uricemia and MetS. The current study aimed to elucidate the relationship between the lower end of UA and MetS in elderly. Subjects aged ≥ 60 years who underwent routine health checkups were enrolled, and 10,579 were eligible for analysis. A cross-sectional study was first performed to determine the correlation between MetS and UA. The subjects were divided into two groups according to the lowest male MetS prevalence in each UA level (UA ≤ 5 and >5 mg/dl). A longitudinal study then excluded subjects with MetS at baseline to validate the UA level of those with the lowest incidence of MetS. In the prevalence of MetS in different UA levels, there was a J-shaped curve in males but a linear relationship in females. In males, waist circumference, systolic blood pressure, high-density lipoprotein, and triglyceride were correlated with UA in univariate analysis, but high-density lipoprotein became insignificant in multivariate analysis in UA >5 mg/dl (UA-high). Only fasting plasma glucose (FPG) was significantly related to UA ≤ 5 mg/dl (UA-low). The UA level of 4.5-5 mg/dl had the lowest risk of having MetS in odds ratio, log-rank test, and hazard ratio. A J-shaped phenomenon exists between UA and MetS in elderly men but not in elderly women and FPG seem to be the key factor in this. Lower UA does not provide benefits in elderly men. The new UA control strategy for the elderly warrants further investigation.