Relationship Between Urinary Uranium and Cardiac Geometry and Left Ventricular Function: The Strong Heart Study.

Background: Uranium is a potentially cardiotoxic, nonessential element commonly found in drinking water throughout the United States.

Objectives: The purpose of this study was to evaluate if urinary uranium concentrations were associated with measures of cardiac geometry and function among American Indian young adults from the Strong Heart Family Study.

Methods: Urinary uranium was measured among 1,332 participants free of diabetes, cardiovascular disease, and <50 years of age at baseline (2001-2003). Transthoracic echocardiography and blood pressure were assessed at baseline and at a follow-up visit (2006-2009). We estimated adjusted mean differences in cardiac geometry and function measures at baseline and follow-up using linear mixed-effect models with a random intercept and slope over time.

Results: Median (interquartile range) uranium was 0.029 (0.045) μg/g creatinine. In fully adjusted cross-sectional models, a log-doubling of urinary uranium was positively associated with left ventricular (LV) mass index (mean difference: 0.49 g/m, 95% CI: 0.07-0.92 g/m), left atrial systolic diameter (0.01 cm/m, 0.01-0.02 cm/m), and stroke volume (0.66 mL, 0.25-1.08 mL) at baseline. Prospectively, uranium was associated with increases in left atrial diameter (0.01 cm/m, 0.01-0.02 cm/m), pulse pressure (0.28 mm Hg, 0.05-0.52 mm Hg), and incident LV hypertrophy (odds ratio: 1.25, 95% confidence interval: 1.06, 1.48).

Conclusions: Urinary uranium levels were adversely associated with measures of cardiac geometry and LV function among American Indian adults, including increases in pulse pressure and LV hypertrophy. These findings support the need to determine the potential long-term subclinical and clinical cardiovascular effects of chronic uranium exposure, and the need for future strategies to reduce exposure.