Difference in 24-hour urine sodium excretion between controlled and uncontrolled patients on antihypertensive drug treatment

The objective of this study was to evaluate the association between sodium intake and blood pressure (BP) control in hypertensive patients taking antihypertensive medications by using 24-hour urine collection and 24-hour ambulatory BP. This is a cross-sectional community-based study and conducted in 2011 and 2012. A total of 1128 participants were recruited from five cities in Korea. Among them, 740 participants who had complete 24-hour urine collection and valid 24-hour ambulatory BP data were included in this study. Participants were divided into four groups: normotensives (NT, n = 441), untreated hypertensive patients (UTHT, n = 174), controlled hypertensive patients (CHT, n = 62), and uncontrolled hypertensive patients (UCHT, n = 63). UCHT and CHT groups showed higher mean age than NT and UTHT groups. UCHT and UTHT groups showed higher 24-hour systolic BP (SBP) and diastolic BP (DBP) than NT and CHT groups. UCHT group had the highest level of 24-hour urine sodium. Multivariate analysis adjusted with age, gender, body mass index, estimated glomerular filtration rate, and use of diuretics showed higher level of 24-hour urine sodium in UCHT group than that in CHT group. Multivariate logistic regression analysis revealed independent association of the amount of 24-hour urine sodium with uncontrolled BP in hypertensive patients on antihypertensive drug treatment. Higher level of 24-hour urine sodium excretion in uncontrolled hypertensive patients suggests that excessive sodium intake could be associated with blunted BP lowering efficacy of antihypertensive medications.