Dysregulated mineral metabolism in patients with acute kidney injury and risk of adverse outcomes

Summary Objective Numerous studies have evaluated the prevalence and importance of vitamin D deficiency among patients with chronic kidney disease and end‐stage renal disease; however, little is known about vitamin D levels in acute kidney injury ( AKI ). We evaluated the association between vitamin D metabolites and clinical outcomes among patients with AKI . Design Prospective cohort study. Patients A total of 30 participants with AKI and 30 controls from general hospital wards and intensive care units at a tertiary care hospital were recruited for the study. Measurements Plasma levels of 25‐hydroxyvitamin D [25( OH )D], 1,25‐dihydroxyvitamin D [1,25( OH ) 2 D], 24R,25‐dihydroxyvitamin D 3 , vitamin D binding protein ( VDBP ) and fibroblast growth factor 23 ( FGF 23) were measured within 24 hours of AKI onset and 5 days later. Bioavailable 25( OH )D and 1,25( OH ) 2 D levels, defined as the sum of free‐ and albumin‐bound 25( OH )D and 1,25( OH ) 2 D, were estimated using equations. Results Compared to controls, participants with AKI had lower levels of 1,25( OH ) 2 D [17 (10–22) vs 25 (15–35) pg/ml, P  = 0·01], lower levels of VDBP [23 (15‐31) vs 29 (25–36) mg/dl, P  = 0·003] and similar levels of bioavailable 25( OH )D and 1,25( OH ) 2 D at enrolment. Levels of bioavailable 25( OH )D were inversely associated with severity of sepsis in the overall sample ( P  < 0·001). Among participants with AKI , bioavailable 25( OH )D, but not other vitamin D metabolites, was significantly associated with mortality after adjusting for age and serum creatinine (adjusted odds ratio per 1 SD ln [bioavailable 25( OH )D] = 0·16, 95% confidence interval = 0·03–0·85). Conclusions Bioavailable 25( OH )D could have a role as a biomarker or mediator of adverse outcomes among patients with established AKI .