Abstract P100: Associations Between Urinary Biomarkers at Baseline and Salt and Potassium Sensitivity: The GenSalt Study

Introduction: Salt sensitivity of blood pressure is associated with an increased risk of hypertension and cardiovascular disease. Measurement methods of salt sensitivity of BP are inconvenient thus identifying biomarkers for salt sensitivity of BP has important clinical significance. Hypothesis: The urinary excretion of dopamine, kallikrein, norepinephrine and uromodulin at baseline are associated with salt sensitivity of BP. Methods: The Genetic Epidemiology Network of Salt Sensitivity (GenSalt) (n=1887) and GenSalt Replication (n=690) studies dietary interventions included a 3-day baseline exam, 7-day low sodium feeding, a 7-day high sodium feeding, and a 7-day high sodium feeding with potassium supplementation. Baseline urinary dopamine, kallikrein, norepinephrine, and uromodulin were measured by ELISA methods. Salt and potassium sensitivity were defined as change in SBP and DBP during dietary intervention. Urinary biomarkers below limit of detection (LOD) were replaced using LOD/√2 and censored likelihood multiple imputation (CLMI). Linear models between standardized log transformed urinary biomarkers and change in SBP and DBP were assessed after adjustment for age, baseline BP, sex, education, physical activity, smoking status, alcohol intake, 24-hour sodium excretion and GenSalt cohort. Results: Norepinephrine was positively associated with SBP in CLMI models (0.10 mmHg, CI: 0.00, 0.19) and DBP in LOD/√2 models (0.31 mmHg, CI: 0.05, 0.57) and CLMI models (0.10 mmHg, CI: 0.02, 0.18) during high sodium diet. Uromodulin was associated with decreased SBP in LOD/√2 models (-0.36 mmHg, CI: -0.57, -0.14) and CLMI models (-0.19 mmHg, CI: -0.31, -0.08) during potassium supplementation. Similarly, dopamine was positively associated with DBP during high sodium diet and negatively associated with DBP during potassium supplementation. Conclusion: These data indicate urinary biomarkers dopamine, norepinephrine and uromodulin are associated with BP salt sensitivity and may be used in risk stratification.