Urinary angiotensinogen excretion and ambulatory blood pressure.
Previous studies have demonstrated that urinary angiotensinogen excretion, a biomarker of the intrarenal renin-angiotensin system activity, is associated with clinic blood pressure (BP). In the present study, we investigated the determinants of urinary angiotensinogen excretion and its associations with ambulatory BP. The study participants were suspected hypertensive patients being off antihypertensive medication for at least 2 weeks and referred to our hypertension clinic for 24-h ambulatory BP monitoring. Ambulatory hypertension was defined as a 24-h BP of at least 130 mmHg systolic or 80 mmHg diastolic. We collected a first morning urine sample for the measurement of angiotensinogen by ELISA kits. The 446 participants (mean age 51.7 years) included 218 (48.9%) men, and 275 (61.7%) patients had ambulatory hypertension. In addition to age and sex, 24-h urinary sodium excretion was an independent determinant of urinary angiotensinogen-to-creatinine ratio (P = 0.0008). Urinary angiotensinogen-to-creatinine ratio was 34% (P = 0.04) and 82% (P ≤ 0.0001) higher in tertiles 2 and 3 of 24-h urinary sodium excretion, respectively, than in tertile 1. In multivariate analyses, urinary angiotensinogen-to-creatinine ratio was significantly and positively associated with clinic and ambulatory BP (P ≤ 0.02) and the prevalence of ambulatory hypertension [odds ratio (95% confidence interval) associated with two-time increase, 1.24 (1.09-1.39); P = 0.0007]. Urinary angiotensinogen excretion is higher with greater urinary sodium excretion, and is associated with clinic and ambulatory BP.