Abstract P150: Aldosterone Dysregulation Increases Cardiovascular Risk in African-American Youth

Abstract

Background: The prevalence of hypertension and blood pressure-related target organ damage in African-Americans is among the highest in the world. We hypothesize that this is in part due to aldosterone dysregulation among African-Americans beginning in youth and leading to the early development of cardiovascular disease in this population. To begin to test this hypothesis, we examined ethnic differences in aldosterone regulation in normal, healthy adolescents. Methods: The subjects in this study were 145 (60 Caucasian, 85 African-American) healthy, normotensive youth aged 15–19 years. Testing was performed following 72 hours on a controlled sodium diet. Testing consisted of the collection of aldosterone, systolic blood pressure (SBP), and urinary sodium excretion (U Na V) during continuous water intake (400 ml total) over a 2 hour period. An echocardiogram was also performed to measure target organ changes. Log transformations were performed on aldosterone levels prior to analyses. Results: African-American compared to Caucasian subjects had higher casual SBP (109±10 v 104±10; p=.006) and relative wall thickness (0.32±.03 v 0.34±.04; p=.003). During the testing procedure African-Americans also had lower levels of aldosterone (4.78±.6 v 4.35±.6 pg/ml; p =.001). In the Caucasian subjects only, aldosterone was inversely correlated with U Na V (r=−0.427; p=.001) and U Na V was positively correlated with SBP (r=0.356; p=.001). The subjects were divided into those in the upper and lower quartiles of salt intake for further analysis. The interaction between race and salt intake was significant for aldosterone (F=7.173; p=.008). Caucasian subjects with high salt intake had lower aldosterone (4.56±.59 v 5.02±0.59 pg/ml). However, aldosterone levels did not differ by salt intake in African-Americans. Summary and Conclusion: African-American subjects did not show the expected associations between aldosterone and the pressure natriuresis relation. Furthermore, African-Americans on the high salt intake failed to suppress aldosterone. These findings are consistent with our hypothesis that aldosterone dysregulation in youth may lead to the early development of cardiovascular disease in Africans-Americans.