High urinary sodium is associated with increased carotid intima-media thickness in normotensive overweight and obese adults

Abstract

Background: Increased dietary sodium has been reported to increase cardiovascular disease (CVD) risk, perhaps through blood pressure (BP)-independent vascular remodeling. Carotid intima-media thickness (IMT) is an accepted measure of structural vascular remodeling and a strong predictor of CVD. This study aimed to determine whether urinary sodium is positively associated with carotid IMT in normotensive overweight and obese adults.

Methods: We evaluated baseline data from 258 participants in the Slow Adverse Vascular Effects (SAVE) clinical trial. Urinary sodium was measured from one 24-h urine collection from each individual. Carotid IMT was measured using high-resolution B-mode ultrasonography. Participants were categorized into quartiles of urinary sodium.

Results: There was a significant positive trend with greater IMT associated with increasing urinary sodium quartile in univariate linear regression (P = 0.047). This trend was significant when adjusting for age, sex, race, and systolic BP (SBP) (P = 0.03) as well as in a fully adjusted model (P = 0.04). In pairwise comparisons, the highest urinary sodium quartile had a significantly greater mean IMT (0.62 mm) than the lowest urinary sodium quartile (0.59 mm) after adjustment for age, sex, race, and SBP (P = 0.04). This comparison lost significance after the addition of BMI.

Conclusions: In our community-based sample of normotensive overweight and obese adults, we observed a significant positive trend in carotid IMT with increasing quartile of urinary sodium. If the ongoing clinical trial confirms this relationship between sodium and carotid IMT, it would lend support to efforts to decrease sodium intake in overweight and obese individuals.

Figure 1. Unadjusted and Adjusted Mean Average IMT by Urinary Sodium Quartile

Increasing urinary sodium quartile is shown across the horizontal axis for each model. Quartiles of urinary sodium are Q1: 48-143 mEq/24hr, Q2: 144-179 mEq/24hr, Q3: 180-224 mEq/24hr, Q4: 225-415 mEq/24hr. Trend P values are for linear trend in mean carotid intima-media thickness (IMT) by sodium quartile. Pairwise comparison p values are adjusted for multiple comparisons by Dunnett’s method. Model 1. Mean IMT adjusted for age, sex, race (black, non-black), systolic blood pressure Model 2. Model 1 + BMI, aldosterone, LDL cholesterol, triglycerides, homeostasis model assessment of insulin resistance index (HOMA), C reactive protein, adiponectin, ever smoker Model 1: N=258, Model 2: N=253