PS-BPC12-8: ASSOCIATION OF URIC ACID WITH BLOOD PRESSURE LEVEL IN ESSENTIAL HYPERTENSION: DIFFERENCES ACCORDING TO DIPPING PATTERN OF NOCTURNAL BLOOD PRESSURE

Abstract

Objective: In essential hypertensive patients, independent of the degree of hypertension, a non-dipping blood pressure pattern is a risk factor for the development of cardiovascular diseases. Serum uric acid level was demonstrated to be an independent predictor of developing hypertension. The increase of uric acid promotes oxidative stress and inflammation, which then enhances endothelial dysfunction. In this study, the association of serum uric acid with 24 hour average blood pressure level was investigated from differences in patterns of circadian blood pressure in patients with essential hypertensive patients. Design and method: In 154 untreated essential hypertensive patients (86 males, average age 56 ± 12 years) without chronic kidney disease (urinary albumin excretion less than 300 mg/g of creatinine and estimated glomerular filtration rate 60 mL/min/1.73m2 or more), 24 hour ambulatory blood pressure monitoring and blood sampling were performed. In blood samples, biochemical parameters including highly sensitive CRP (hsCRP) and nitric oxide metabolites (NOx) were measured. Non-dipper status was defined as a decrease in nocturnal systolic blood pressure < 10 %. The patients were divided into two groups according to their nocturnal systolic blood pressure status: 56 patients with non-dipper status and 98 patients with dipper status. Results: 24 hour systolic blood pressure was higher in the non-dipper patients than in the dipper group (148 ± 17 vs 139 ± 16 mmHg, p < 0.001), whereas diastolic blood pressure and pulse rate did not differ between the two groups. The non-dipper group was characterized by increased serum uric acid and hsCRP and decreased plasma NOx level compared with the dipper group (6.0 ± 1.7 mg/dL, 0.10 ± 0.15 mg/dL, 41.4 ± 25.3 μmol/L in the non-dipper group vs 5.5 ± 1.5, 0.07 ± 0.11, 50.1 ± 31.3 in the dipper group, p < 0.05, respectively). 24 hour systolic blood pressure correlated positively with serum uric acid and hsCRP and negatively with plasma NOx in the non-dipper group (r = 0.25, 0.32, -0.25, p < 0.05, respectively), but did not so in the dipper group. Furthermore, in the non-dipper group, multiple regression analysis revealed that serum uric acid was an independent determinant for 24 hour systolic blood pressure level together with hsCRP, and plasma NOx (R2 0.25, p < 0.01). Conclusions: These data indicate that the elevation of serum uric acid could associate with persistently elevated blood pressure accompanied with micro-inflammation and vascular endothelial dysfunction in essential hypertensive patients with an attenuated nocturnal blood pressure dipping.