Nutritional vitamin D in dialysis patients: what to D-iscern?

A et al. Identification of neutrophil gelatinase-associated lipocalin as a novel early urinary biomarker for ischemic renal injury. Dent CL, Ma Q et al. Urine NGAL predicts severity of acute kidney injury after cardiac surgery: a prospective study. Dent C, Tarabishi R et al. Neutrophil gelatinase-associated lipocalin (NGAL) as a biomarker for acute renal injury after cardiac surgery. Plasma and urine neutrophil gelatinase-associated lipocalin in septic versus non-septic acute kidney injury in critical illness. Dent C, Pfriem H et al. NGAL is an early predictive bio-marker of contrast-induced nephropathy in children. A et al. Neutrophil gelatinase-associated lipocalin in adult septic patients with and without acute kidney injury. A et al. Serum neutrophil gelatinase-associated lipocalin at inception of renal replacement therapy predicts survival in critically ill patients with acute kidney injury. Crit Care 2010; 14: R9 9. Nickolas TL, O'Rourke MJ, Yang J et al. Sensitivity and specificity of a single emergency department measurement of urinary neutrophil gelatinase-associated lipocalin for diagnosing acute kidney injury. Urine neutrophil gelatinase-associated lipocalin: an independent predictor of adverse outcomes in acute kidney injury. Endocytic delivery of lipocalin-siderophore-iron complex rescues the kidney from ischemia-reperfu-sion injury. A et al. Early prediction of urinary tract infection with urinary neutrophil gelatinase associated lipocalin. Worldwide, ∼2 million patients rely on chronic dialysis therapy to sustain their life [1,2]. Despite advances in therapies and technology, mortality and morbidity in the dialysis population remain high. Cardiovascular disease is the leading cause of mortality in this population [3] and the search remains active for 'modifiable factors' that will improve outcomes in this patient population. Vitamin D, traditionally thought to be involved only in bone and mineral metabolism, has been increasingly reported to have significant extraskeletal actions [4,5]. These include its effects on monocyte–macrophages (expression of the cathelicidin antimicrobial peptide), lymphocytes (cytokine release), pancreas (insulin production) and kidney (renin production). Studies have suggested that vitamin D has anticancer properties through its effects on cellular proliferation , differentiation, apoptosis and angiogenesis. It has been shown to be involved in the growth and proliferation of vascular smooth muscle cells and cardiomyocytes [4,6]. Vitamin D traditionally exerts its effects on bone and mineral metabolism in its hormone form, 1,25-dihydroxyvitamin D (1,25-D). In patients with normal renal function, inadequate supply of substrate 25-hydroxyvitamin D (25-D) will stimulate the 1-α hydroxylase enzyme in proximal renal tubular cells to maintain levels of 1,25-D, an effect mediated via an increase in parathyroid …