Abstract 832: Association Between Urinary Sodium Excretion and Left Ventricular Mass: Coronary Artery Risk Development in Young Adults Study (CARDIA)
Background Among a cohort of young adults, we determined whether sodium intake as measured by the average of three 24-hour urinary sodium excretions (UNa), is associated with echocardiographic left ventricular mass (LVM).
Methods and Results CARDIA is a multicenter study initiated in 1985–86 with LVM and UNa determined in parallel in 1,042 participants at the Year 5 examination (1990 –91). LVM was again assessed 5 years later in 2 of the 4 clinics (n=399). Linear and logistic regression analysis was used with indexed LVM/height2.7 (LVMI) as the dependent variable. Mean age was 30±3.6 yrs, mean SBP was 108±11.7 mmHg with only 4% of the participants being hypertensive. Mean UNa was 175.6±131mmol/mL. Adjusted for age, sex, education, and race, greater UNa was associated with greater LVMI (β=0.0072, SD=0.002, p=0.001). Participants in the highest and lowest quartiles of UNa had the greatest and lowest LVMI (37.5g/m2.7 vs. 34g/m2.7; p<0.001). Each additional year of education was associated with an average 0.338g/m2.7 lower LVMI (SD=0.132; p=0.01). Education category impacted the relationship between UNa and LVMI (p for interaction <0.001), where in the highest quartile of UNa the protective effect of education was greatly attenuated. On adjusted prospective analysis, each 10mmol/mL increase in UNa was associated with an 8% greater odds of being in the highest LVMI quartile 5 years later (OR 1.08; CI 1.04 –1.11).
Conclusions Lower UNa is associated with lower LVMI both cross-sectionally and prospectively among normotensive young adults. The association varied by educational attainment with a protective effect of higher education particularly for those in the lower categories of UNa.