24-Hour Urine Phosphorus Excretion and Mortality and Cardiovascular Events

Abstract

SummaryBackground and objectives Higher morning serum phosphorus has been associated with cardiovascular disease (CVD) in patients with or without CKD. In patients with CKD and a phosphorous level .4.6 mg/dl, the Kidney Disease Improving Global Outcomes guidelines recommend dietary phosphorus restriction. However, whether phosphorus restriction influences serum phosphorus concentrations and whether dietary phosphorus is itself associated with CVD or death are uncertain.Design, setting, participants, & measurements Among 880 patients with stable CVD and normal kidney function to moderate CKD, 24-hour urine phosphorus excretion (UPE) and serum phosphorus were measured at baseline. Participants were followed for a median of 7.4 years for CVD events and all-cause mortality.Results Mean 6 SD age was 67611 years, estimated GFR (eGFR) was 71622 ml/min per 1.73 m 2 , and serum phosphorus was 3.760.6 mg/dl. Median UPE was 632 (interquartile range, 439, 853) mg/d. In models adjusted for demographic characteristics and eGFR, UPE was weakly and nonsignificantly associated with serum phosphorus (0.03 mg/dl higher phosphorus per 300 mg higher UPE; P=0.07). When adjusted for demographics, eGFR, and CVD risk factors, each 300-mg higher UPE was associated with 17% lower risk of CVD events. The association of UPE with all-cause mortality was not statistically significant (hazard ratio, 0.93; 95% confidence interval, 0.82 to 1.05). Results were similar irrespective of CKD status (P interactions . 0.87).Conclusions Among outpatients with stable CVD, the magnitude of the association of UPE with morning serum phosphorus is modest. Greater UPE is associated with lower risk for CVD events. The association was similar for all-cause mortality but was not statistically significant.

The importance of klotho in phosphate metabolism and kidney disease

“…A recent report of 880 adults from the Heart and Soul Study, described an association between higher urinary phosphate excretion with lower risk of cardiovascular events and a non‐significant association with mortality . One quarter of the cohort in this study had CKD and analysis of FGF23 levels revealed an association with mortality which was modified by FEPi .…”

Dietary Phosphorus Intake and the Kidney

“…In the Heart and Soul study, an observational study of 880 adults with a history of coronary heart disease, 24-h urine phosphorus excretion was not associated with mortality (third tertile versus first tertile aHR 0.78; 95% CI, 0.56–1.07) (124). However, data from this study suggest there may be serious issues with using 24-h urine phosphorus to estimate habitual phosphorus intake.…”

Dysmagnesemia in Hospitalized Patients: Prevalence and Prognostic Importance

“…We found that more patients with Mg levels of 2.9 mg/dL or higher were taking oral Mg (Supplemental Table 2, available online at http://www.mayoclinic proceedings.org). In the fully adjusted model (model 4, which included hyperphosphatemia [implicated in mortality [26][27][28] ]), the risk for hospital mortality and being discharged to a care facility was increased when Mg levels were 2.3 mg/dL or higher. The mortality risk increased progressively with increasing Mg level (Figure 3, B).…”