Kidney international
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Kidney international · Jul 2012
Bioavailable vitamin D is more tightly linked to mineral metabolism than total vitamin D in incident hemodialysis patients.
Prior studies showed conflicting results regarding the association between 25-hydroxyvitamin D (25(OH)D) levels and mineral metabolism in end-stage renal disease. In order to determine whether the bioavailable vitamin D (that fraction not bound to vitamin D-binding protein) associates more strongly with measures of mineral metabolism than total levels, we identified 94 patients with previously measured 25(OH)D and 1,25-dihydroxyvitamin D (1,25(OH)(2)D) from a cohort of incident hemodialysis patients. Vitamin D-binding protein was measured from stored serum samples. ⋯ Bioavailable, but not total, 25(OH)D and 1,25(OH)(2)D were each significantly correlated with serum calcium. In univariate and multivariate regression analysis, only bioavailable 25(OH)D was significantly associated with parathyroid hormone levels. Hence, bioavailable vitamin D levels are better correlated with measures of mineral metabolism than total levels in patients on hemodialysis.
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Kidney international · Jul 2012
CommentA physician's perseverance uncovers problems in a key nephrology study.
The Normal Hematocrit Cardiac Trial, published in 1998, was a foundational study testing erythropoietin analog treatment to normal hematocrit targets. It served as a warning that erythropoietin replacement was not a panacea. ⋯ Coyne shows that the published results did not completely and clearly represent the study's actual results. We discuss the implications and make recommendations to prevent such occurrences.