Serum 25(OH)-cholecalciferol concentration is associated with hemoglobin level and erythropoietin resistance in patients on maintenance hemodialysis.

BACKGROUND: Resistance to erythropoiesis-stimulating agents (ESAs) has been observed in patients with chronic kidney disease (CKD) and it is associated with clinical outcomes. The presence of ESA resistance cannot always be explained by the known risk factors of the condition, suggesting that additional factors may be involved. We wanted to test the hypothesis that vitamin D insufficiency is associated with lower hemoglobin (Hb) and ESA resistance in patients on maintenance hemodialysis (HD). METHODS: Data from patients receiving maintenance HD in a single dialysis center were extracted from the medical records in a retrospective chart review. Basic patient characteristics and laboratory data including Hb, serum albumin, intact parathyroid hormone and serum 25(OH)-cholecalciferol (25(OH)D(3)) levels were collected. ESA dose and Kt/V were extracted from the dialysis charts. Correlation analysis and multivariate linear regression analysis were used to reveal potential independent associations between clinical and laboratory parameters and ESA resistance. RESULTS: Data from 142 patients were analyzed. Serum 25(OH)D(3) concentration was significantly correlated with Hb (ρ = 0.186, p < 0.05) and also with ESA dose/Hb index (ρ = 0.230, p < 0.01). In multivariable regression analyses, serum 25(OH)D(3) concentration remained significantly associated with both Hb and ESA dose/Hb index after controlling for potentially important confounders. CONCLUSION: Serum 25(OH)D(3) concentration is independently associated with erythropoietin responsiveness in CKD patients on maintenance HD. If this association will be confirmed, treatment trials looking at the effect of vitamin D supplementation on anemia treatment in CKD patients may be warranted.

Serum 25(OH)-vitamin D levels and bone metabolism in patients on maintenance hemodialysis.

AIMS: An increasing amount of evidence suggests that 25-hydroxy vitamin D3 (25(OH)D3) may contribute to the bone health of patients with chronic kidney disease (CKD). The underlying vitamin D status of these patients, however, has often been neglected. In a cross-sectional study we assessed the association between vitamin D status and parathyroid function, bone turnover, bone mass and structure in patients on maintenance hemodialysis. METHODS: 69 patients on maintenance hemodialysis were assessed by bone densitometry (DEXA) and quantitative bone ultrasound (QUS). Serum 25-hydroxy vitamin D3 levels, serum markers of bone turnover and clinical data were tabulated. RESULTS: A high prevalence of potentially significant vitamin D3 deficiency was found in this patient group: 59% of the patients had a 25(OH)D3 level below 20 nmol/l. There was a significant negative correlation between serum 25(OH)D3 levels and serum intact parathyroid hormone (iPTH) (r = -0.231, p < 0.05), and this association remained significant after controlling for potential covariables. Furthermore, we show here that serum 25(OH)D3 concentration is positively correlated with bone mineral density (BMD) measured at the radius (r = 0.424, p < 0.01). Finally, we show for the first time that 25(OH)D3 levels are significantly and independently correlated with broadband ultrasound attenuation (beta = 0.262, p < 0.05) measured with calcaneal quantitative bone ultrasound (QUS) in patients with chronic renal failure. CONCLUSION: Vitamin D3 deficiency may contribute to the impaired bone health of patients on maintenance dialysis.