The Relationship between Urine Uromodulin and Blood Pressure Changes: the DASH-Sodium Trial.

BACKGROUND Uromodulin modulates the sodium-potassium-two-chloride transporter in the thick ascending limb of the loop of Henle, and its overexpression in murine models leads to salt-induced hypertension. We hypothesized that individuals with higher baseline levels of urine uromodulin will have a greater increase in systolic blood pressure (SBP) for the same increase in sodium compared to those with lower uromodulin levels. METHODS We used data from 157 subjects randomized to the control diet of the DASH-Sodium trial who were assigned to 30 days of low (1500 mg/d), medium (2400 mg/d), and high salt (3300 mg/d) diets in random order. Blood pressure was measured pre-randomization, and then weekly and at five visits during the last nine days of each feeding period. We evaluated the association of pre-randomization urine uromodulin with change in SBP between diets, as measured by the average at the end of each feeding period, using multivariable linear regression. RESULTS Baseline urine uromodulin stratified by tertiles was ≤17.64, 17.65 - 31.97, and ≥31.98 μg/mL. Across the tertiles, there were no significant differences in SBP at baseline, nor was there a differential effect of sodium diet on SBP across tertiles (low to high, p = 0.81). After adjusting for age, sex, body mass index, and race, uromodulin levels were not significantly associated with SBP change from low to high sodium diet (p = 0.42). CONCLUSIONS In a randomized trial of different levels of salt intake, higher urine uromodulin levels were not associated with a greater increase in blood pressure in response to high salt intake.