Impact of cardiovascular risk factors and inflammatory status on urinary 8-OHdG in essential hypertension

The urinary concentrations of 8-hydroxy-2'-deoxyguanosine (8-OHdG) reflect the oxidation status of hypertensive subjects and it can be used for monitoring oxidative stress changes. However, the influence of cardiovascular risk factors and inflammation on the urinary levels of this marker in hypertension (HT) has never evaluated. The purpose of this study was to analyze the impact of cardiovascular risk factors, and established inflammatory markers on 8-OHdG in essential HT.

We studied 149 asymptomatic hypertensive patients (61 ± 14 years). A routine physical examination, laboratory analyses, and echo-Doppler study were performed. Urinary 8-OHdG and plasma tumor necrosis factor-α (TNF-α), soluble TNF receptor 1 (sTNF-R1), soluble TNF receptor 2 (sTNF-R2), and interleukin-6 (IL-6) were determined.

8-OHdG/creatinine levels were higher in hypertrophic patients (P = 0.022) and correlated with left ventricular mass index (P < 0.01). When 8-OHdG/creatinine was compared according to obesity and diabetes in our hypertensive subjects, no significant differences were found. 8-OHdG/creatinine was increased in hypertensive smokers (P = 0.032) and women (P = 0.006). Furthermore, 8-OHdG/creatinine correlated with TNF-α, sTNF-R1, sTNF-R2 (P < 0.0001), and with IL-6 (P < 0.05). A multivariate linear regression analysis showed that gender, smoking, and TNF-α were independent factors of 8-OHdG/creatinine.

Urinary 8-OHdG was increased in hypertensive patients with hypertrophy even under medical treatment. The presence of other cardiovascular risk factors on top of HT do not alter the concentrations of this oxidative stress marker, only smoking increasing its levels. TNF-α is an independent factor of 8-OHdG. These data suggest that this urinary marker gives specific additional information, further than blood pressure control alone, when evaluating hypertensive patients.