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.
Prospective cohort study.
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.
Plasma levels of 25-hydroxyvitamin D [25(OH)D], 1,25-dihydroxyvitamin D [1,25(OH)2D], 24R,25-dihydroxyvitamin D3, vitamin D binding protein (VDBP) and fibroblast growth factor 23 (FGF23) were measured within 24 hours of AKI onset and 5 days later. Bioavailable 25(OH)D and 1,25(OH)2D levels, defined as the sum of free- and albumin-bound 25(OH)D and 1,25(OH)2D, were estimated using equations.
Compared to controls, participants with AKI had lower levels of 1,25(OH)2D [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)2D 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).
Bioavailable 25(OH)D could have a role as a biomarker or mediator of adverse outcomes among patients with established AKI.