Association of sodium and potassium intake with left ventricular mass: Coronary artery risk development in young adults

High salt intake may affect left ventricular mass (LVM). We hypothesized that urinary sodium (UNa) and sodium/potassium ratio (UNa/K) are associated with LVM in a predominantly normotensive cohort of young adults. The Coronary Artery Risk Development in Young Adults (CARDIA) Study is a multicenter cohort of black and white men and women aged 30±3.6 years at the time of baseline echocardiographic examination (1990-1991). 2D guided M-mode LVM indexed to body size (grams per meter ^2.7) was calculated, and UNa and potassium excretion assessed (average of three 24-hour urinary samples, n=1042). Linear and logistic regression analysis was used. Participants were 57% women and 55% black. Only 4% were hypertensive. UNa, urinary potassium, and UNa/K ratios were (mean±SD) 175.6±131.0, 56.4±46.3, and 3.4±1.4 mmol/24 h, respectively. Participants in the highest versus the lowest UNa excretion quartile had the greatest LVM (37.5 versus 34.0 g/m ^2.7; P<0.001). Adjusted for age, sex, education, and race, LVM averaged 0.945 g/m ^2.7 higher per SD of UNa/K (P=0.001). The relationship between UNa/K and LVM persisted among 399 participants with repeat echocardiographic measures 5 years later. In logistic regression analysis adjusted for age, sex, education, and race, each SD higher baseline UNa/K was associated with 23% and 38% greater chances of being in the highest quartile of LVM at baseline (odds ratio: 1.23; P=0.005) and 5 years later (odds ratio: 1.38; P=0.02). A higher sodium/potassium excretion ratio is significantly related to cardiac structure, even among healthy young adults.