Association between Vitamin D Deficiency and Anemia in Patients with End-Stage Renal Disease: A Cross-Sectional Study.

PURPOSE: Despite new treatment strategies, anemia remains the most prevalent complication in patients with end-stage renal disease (ESRD). We investigated whether 25-hydroxyvitamin D [25(OH)D3] deficiency was associated with anemia in ESRD patients. MATERIALS AND METHODS: We reviewed the medical records of 410 ESRD patients who had undergone renal transplantation (RTx) at Yonsei University Health System and who had 25(OH)D3 levels measured at the time of RTx. Patients were divided into two groups based on baseline 25(OH)D3 concentrations: group 1, 25(OH)D3 levels <10 ng/mL; and group 2, 25(OH)D3 levels ≥10 ng/mL. RESULTS: Using multivariate regression models, 25(OH)D3, age, and erythrocyte-stimulating agent (ESA) dose were found to be significantly associated with hemoglobin (Hb) levels [25(OH)D3: ß=0.263, p<0.001; age: ß=0.122, p=0.010; ESA dose: ß=-0.069, p=0.005]. In addition, logistic regression analysis revealed that patients in group 1 had a significantly higher risk for developing anemia (Hb level <10 g/dL) compared to group 2 patients, even after adjusting for potential risk factors for anemia (odds ratio=3.857; confidence interval=1.091-13.632; p=0.036). CONCLUSION: 25(OH)D3 deficiency was significantly associated with anemia in patients with ESRD. Randomized controlled trials are needed to determine whether vitamin D supplementation can improve anemia in these patients.

The relationship of initial transferrin saturation to cardiovascular parameters and outcomes in patients initiating dialysis.

BACKGROUND: The prognostic importance of anemia for cardiovascular (CV) events and mortality has been extensively investigated. However, little is known about the impact of transferrin saturation (TSAT), a marker reflecting the availability of iron for erythropoiesis, on clinical outcome in dialysis patients. METHODS: A total of 879 anemic incident dialysis patients were recruited from the Clinical Research Center for End-Stage Renal Disease in Korea and were divided into 3 groups according to baseline TSAT of ≤20%, 20-40%, and >40%. RESULTS: There were no differences in hemoglobin levels and the proportion of patients on erythropoiesis-stimulating agents or iron supplements among the 3 groups. During a mean follow-up duration of 19.3 months, 51 (5.8%) patients died. CV composite (11.71 vs. 5.55 events/100 patient-years, P = 0.001) and all-cause mortality rates (5.38 vs. 2.31 events/100 patient-years, P = 0.016) were significantly higher in patients with TSAT ≤20% compared to those with TSAT 20-40% (reference group). Cox regression analysis revealed that patients with TSAT ≤20% had 1.62- and 2.19-fold higher risks for CV composite outcome (P = 0.046) and all-cause mortality (P = 0.030). Moreover, TSAT ≤20% was significantly associated with left ventricular hypertrophy [odds ratio (OR)  = 1.46], high-sensitivity C-reactive protein ≥3 mg/dL (OR = 2.09), N-terminal pro B-type natriuretic peptide ≥10000 pg/mL (OR  = 2.04), and troponin-T≥0.1 ng/mL (OR  = 2.02), on logistic regression analysis. CONCLUSIONS: Low TSAT was a significant independent risk factor for adverse clinical outcome in incident dialysis patients with anemia, which may be partly attributed to cardiac dysfunction and inflammation.