Race, Mineral Homeostasis and Mortality in Patients with End-Stage Renal Disease on Dialysis.

BACKGROUND: Abnormalities in mineral homeostasis are ubiquitous in patients on dialysis, and influenced by race. In this study, we determine the race-specific relationship between mineral parameters and mortality in patients initiating hemodialysis. METHODS: We measured the levels of fibroblast growth factor 23 (FGF23) and 25-hydroxyvitamin D (25 D) in 184 African American and 327 non-African American hemodialysis patients who enrolled between 1995 and 1998 in the Choices for Healthy Outcomes in Caring for ESRD Study. Serum calcium, phosphorus, parathyroid hormone (PTH) and total alkaline phosphatase levels were averaged from clinical measurements during the first 4.5 months of dialysis. We evaluated the associated prospective risk of mortality using multivariable Cox proportional hazards models stratified by race. RESULTS: PTH and total alkaline phosphatase levels were higher, whereas calcium, phosphorus, FGF23 and 25 D levels were lower in African Americans compared to those of non-African Americans. Higher serum phosphorus and FGF23 levels were associated with greater mortality risk overall; however, phosphorus was only associated with risk among African Americans (HR 5.38, 95% CI 2.14-13.55 for quartile 4 vs. 1), but not among non-African Americans (p-interaction = 0.04). FGF23 was associated with mortality in both groups, but more strongly in African Americans (HR 3.91, 95% CI 1.74-8.82 for quartiles 4 vs. 1; p-interaction = 0.09). Serum calcium, PTH, and 25 D levels were not consistently associated with mortality. The lowest and highest quartiles of total alkaline phosphatase were associated with higher mortality risk, but this did not differ by race (p-interaction = 0.97). CONCLUSIONS: Aberrant phosphorus homeostasis, reflected by higher phosphorus and FGF23, may be a risk factor for mortality in patients initiating hemodialysis, particularly among African Americans.

Americans' use of dietary supplements that are potentially harmful in CKD.

BACKGROUND: The prevalence in the United States of dietary supplement use that may be harmful to those with chronic kidney disease (CKD) is unknown. We sought to characterize potentially harmful supplement use by individual CKD status. STUDY DESIGN: Cross-sectional national survey (National Health and Nutrition Examination Survey, 1999-2008). SETTING & PARTICIPANTS: Community-based survey of 21,169 nonpregnant noninstitutionalized US civilian adults (aged ≥20 years). PREDICTOR: CKD status (no CKD, at risk of CKD [presence of diabetes, hypertension, and/or cardiovascular disease], stages 1/2 [albuminuria only (albumin-creatinine ratio ≥30 mg/g)], or stages 3/4 [estimated glomerular filtration rate of 15-59 mL/min/1.73 m(2)]). OUTCOME: Self-reported use of dietary supplements containing any of 37 herbs the National Kidney Foundation identified as potentially harmful in the setting of CKD. MEASUREMENTS: Albuminuria and estimated glomerular filtration rate assessed from urine and blood samples; demographics and comorbid conditions assessed by standardized questionnaire. RESULTS: An estimated 8.0% of US adults reported potentially harmful supplement use within the last 30 days. A lower crude estimated prevalence of potentially harmful supplement use was associated with higher CKD severity (no CKD, 8.5%; at risk, 8.0%; stages 1/2, 6.1%; and stages 3/4, 6.2%; P < 0.001). However, after adjustment for confounders, those with or at risk of CKD were as likely to use a potentially harmful supplement as those without CKD: at-risk OR, 0.93 (95% CI, 0.79-1.09); stages 1/2 OR, 0.83 (95% CI, 0.64-1.08); and stages 3/4 OR, 0.87 (95% CI, 0.63-1.18); all versus no CKD. LIMITATIONS: Herb content was not available and the list of potentially harmful supplements examined is unlikely to be exhaustive. CONCLUSIONS: The use of dietary supplements potentially harmful to people with CKD is common regardless of CKD status. Health care providers should discuss the use and potential risks of supplements with patients with and at risk of CKD.