RELATIONSHIP BETWEEN PHOSPHATURIA AND BLOOD PRESSURE: INSIGHTS FROM THE SKIPOGH COHORT

Objective: Hyperphosphataemia is a silent condition, often resulting from advanced chronic kidney disease or excessive dietary intakes. While phosphate has been linked to cardiovascular issues, such as arterial stiffness and left ventricle hypertrophy, its role in blood pressure (BP) regulation has yet to be established. This study examines the relationship between 24-hour urinary phosphate excretion and BP in the Swiss Kidney Project on Genes in Hypertension (SKIPOGH) cohort, accounting for vascular mechanisms involving arterial stiffness. Design and method: We conducted a cross-sectional analysis within the SKIPOGH study involving a general population and family-based cohort. BP was measured by 24-hour ambulatory monitoring, while vascular stiffness was evaluated using carotid-femoral pulse wave velocity (PWV) and the renal resistive index (RRI). Mixed multivariable regression models were used to analyze relationships between phosphaturia and BP, with further adjustments made for PWV and RRI. Covariates included age, sex, body mass index, renal function (eGFR), sodium/potassium excretion ratios, and cardiovascular risk factors. Results: We included 978 participants with complete 24-hour urinary phosphate and BP measurements: 52% were female, with median age of 46 years old, and 19.5% with hypertension. In multivariate models, 24 h phosphaturia showed an inverse association with 24-hour systolic BP (β = -0.96; 95% CI: -1.80 to -0.12; p = 0.02) and diastolic BP (β = -0.52; 95% CI: -1.02 to -0.02; p = 0.04). After adding PWV and RRI to those models, these associations even strengthened for both 24h-systolic BP (β = -1.23; 95% CI: -2.07 to -0.38; p = 0.004), and diastolic BP (β = -0.56; 95% CI: -1.08 to -0.04; p = 0.036). We observed a consistent negative trend across the spectrum of phosphaturia values. Conclusions: In this population-based study, higher 24-hour urinary phosphate excretion was associated with lower systolic and diastolic BP. This association was independent of both vascular stiffness markers as measured by PWV and RRI. Therefore, phosphate intake in a population with normal renal function seem to have rather a protective effect on blood pressure.