Urinary angiotensinogen excretion and ambulatory blood pressure

OBJECTIVE: 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. METHODS: 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. RESULTS: 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]. CONCLUSION: Urinary angiotensinogen excretion is higher with greater urinary sodium excretion, and is associated with clinic and ambulatory BP.