Association Between Circadian Blood Pressure Patterns and Oxidative Stress Parameters in Normotensive Individuals

Background Circadian variation of blood pressure (BP) and nocturnal dipping phenotype are prognostically important. Although nondipping and reverse-dipping phenotypes predict worse cardiovascular outcomes in hypertensive cohorts, their biological correlates in normotensive individuals are less well characterized. This study investigated whether abnormal BP patterns in normotensive individuals are associated with high oxidative stress. Methods This cross-sectional analysis included 127 normotensive individuals (age 21–68 years) who underwent 24-h ambulatory BP monitoring (ABPM) and laboratory measurements of total oxidant status (TOS), total antioxidant status (TAS), and oxidative stress index (OSI). Participants were classified into dippers, nondippers, or reverse-dippers according to nocturnal decline in systolic BP. Statistical comparisons and correlation analyses were conducted. Primary data were obtained from the author’s thesis. Results Marked differences in oxidative stress parameters were observed across circadian BP patterns. TOS increased progressively from dippers to nondippers to reverse-dippers (34.63 ± 9.8, 73.67 ± 14.6, and 85.23 ± 16.9 µmol/L, respectively; p  < 0.001), whereas TAS was markedly lower in nondippers and reverse-dippers than in dippers (106.00 ± 18.2 vs 39.59 ± 11.4 and 45.86 ± 12.7 µmol/L ; p  < 0.001). Consequently, OSI values were substantially higher in individuals with abnormal nocturnal BP patterns, reaching the highest levels in reverse-dippers (22.05 ± 6.9 vs. 84.74 ± 19.3 and 86.32 ± 21.1; p  < 0.001). In the correlation analyses, nocturnal systolic BP decline demonstrated a strong inverse association with OSI (r = − 0.62, p  < 0.001). Conclusion In normotensive individuals, abnormal nocturnal BP patterns, particularly reverse dipping, are associated with substantially increased oxidative stress. Therefore, ABPM may unmask subclinical cardiovascular risk mediation via oxidative mechanisms even when office BP is normal.