ASSOCIATION OF 24-HOUR URINARY SODIUM EXCRETION WITH AMBULATORY BLOOD PRESSURE PARAMETER

Abstract

Objective: As the important effects of sodium intake on blood pressure (BP) and on response to anti-hypertensive medication has been recognized for long times, it has been recommended that dietary sodium intake is restricted in hypertensive patients. However, the relationship between BP and salt is weak in most community studies. Moreover, a study in hypertensive Chinese patients showed that urinary sodium excretion is only related to diastolic BP (DBP) and not to systolic BP (SBP). Therefore, this study was to investigate whether the 24-hour urinary sodium excretion was associated with the ambulatory DBP and not with SBP.

Design and Method: This study was composed of 121 patients who underwent coronary angiography or percutaneous coronary intervention. The 24-hour urine collection was usually performed at admission day 3 or 4. At the same admission day the ambulatory blood pressure monitoring (ABPM) was also performed. Additional ABPM was carried out in the uncontrolled blood pressure situations.

Results: The mean serum creatinine was 0.96 ± 0.53, mean 24-hour sodium excretion 128.54 ± 170.76 and mean 24-hour potassium excretion 33.10 ± 13.99. The mean 24 hour urinary sodium/potassium excretion ratio was 3.62 ± 1.70 and mean 24 hour urinary sodium/creatinine excretion ratio 185.79 ± 523.82 and 24-hour micro-albuminuria 48.87 ± 152.57. The mean 24-hour sodium excretion was associated with sleep-SBP, sleep-DBP, sleep-pulse pressure (PP), wake-PP, 24-hour SBP, 24 PP, 24-hour potassium excretion, 24-hour sodium/potassium ratio and 24-hour sodium/creatinine ratio. After adjustment for age, gender, body mass index and urinary potassium excretion, only sleep-SBP was significantly associated with 24-hour urinary sodium excretion.

Conclusions: Our study showed that 24-hour urinary sodium excretion was only associated with sleep SBP.