Increased Uric Acid Promotes Decline of the Renal Function in Hypertensive Patients: A 10-year Observational Study

Abstract

Uric acid (UA) has shown to be a causal risk factor for the development and progression of renal disease. The aim of this study was to investigate the relationship between changes in the level of UA and trends in the renal function among hypertensive patients during a 10-year observation period. The subjects included 104 hypertensive outpatients (60 women and 44 men, mean age 60±9 (SD) years at the first visit) who had undergone at least five instances of successful 24-hour home urine collection, with the first examination completed between 1998 and 2000 and the last examination completed between 2008 and 2010. The estimated glomerular filtration rate (eGFR) significantly decreased over the 10.4-year observation period, with an average change in eGFR of -0.66/mL/min/year. The uric acid clearance at the last examination was significantly lower than that observed at the first visit, while there were no significant differences in the serum UA levels during this period. The change in serum UA exhibited a significant negative correlation with the change in eGFR (r=-0.34, p<0.01). The patients whose UA level decreased more than 0.5 mg/dL during the observation period demonstrated significantly smaller declines in eGFR compared to those whose UA level increased more than 0.5 mg/dL. In the multivariate analysis, the change in serum UA and the average urinary salt excretion during the observation period were found to be significantly associated with the change in eGFR, independent of age, sex, BP changes or an increased number of antihypertensive drugs. Based on the findings observed over a 10-year observation period, increased UA is suggested to promote decline of the renal function in hypertensive patients. Controlling the level of UA as well as intensively restricting salt intake is required in order to preserve the renal function.