Variation in Sodium Intake and Intra-individual Change in Blood Pressure in Chronic Kidney Disease.

OBJECTIVE: In the kidney disease clinic setting, higher-than-usual blood pressure is often ascribed to recent dietary sodium indiscretion. While clinical trials demonstrate a clear relationship between salt intake and blood pressure on the population level, it is uncertain whether real-world variation in sodium intake within individual chronic kidney disease (CKD) patients is associated with fluctuations in blood pressure. METHODS: We analyzed data from the Phosphorus Normalization Trial, in which participants with CKD eating their usual diets completed at least three 24-hour urine collections over 9 months, from which we measured sodium. Blood pressure was measured at the time of 24-hour urine collections. For each individual participant, we assessed the slope of the relationship between sodium intake and mean arterial blood pressure (MAP). RESULTS: Among 119 participants (mean age 67 years and mean estimated glomerular filtration rate 31 mL/minute/1.73 m2), there was substantial variation in sodium intake as measured by 24-hour urine collections (mean intake 3,903 mg/day, standard deviation 1037 mg/day). Individual participants had highly variable associations between their sodium intake and their MAP; 47% (n = 56) had inverse associations between sodium and MAP, whereas the remainder had positive (salt-sensitive) associations. CONCLUSIONS: Among CKD patients, there is substantial variation in sodium intake but no predictable relationship between dietary sodium and blood pressure in individuals. The frequent dismissal of elevated blood pressure readings as related to recent sodium intake in clinic may be a misapplication of large-scale population data to explain individual variability and may contribute to clinical inertia regarding high blood pressure treatment.

Efficacy and safety of SBR759, a new iron-based phosphate binder.

Treatment of elevated serum phosphorus in hemodialysis patients remains challenging due in part to the lack of a well-tolerated, safe, and effective phosphate binder. Here we report the results of a single-center, open-label, phase I clinical trial of 44 hemodialysis patients to show the safety and efficacy of a novel iron-based phosphate binder, SBR759. After establishing its safety at an initial dose of 3.75 g/day, SBR759 was given to successive cohorts in several divided doses of up to 22.5 g/day. The defined measure of efficacy was the average change in serum phosphorus in the cohorts receiving 11.25 and 15.0 g/day, in whom the mean reduction was 2.1 mg/dl. A clinically and statistically significant reduction in serum phosphorus was found across the entire dose range. All patients were able to achieve mean phosphorus levels within K/DOQI target ranges at the end of the first week. SBR759 was well tolerated within the anticipated clinical dose range of 3.75-15 g/day. No treatment-related serious adverse events were observed nor were there clinically relevant changes in iron indices. While these preliminary studies highlight the clinical efficiency and safety of SBR759, its promise of improved therapeutic options for hyperphosphatemia in patients with chronic kidney disease requires further study.