• Open Access

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

Authors


Correspondence: David E. Leaf, Renal Division, Brigham and Women's Hospital, 75 Francis Street, Boston, MA 02115, USA. Tel.: +1 617-732-5500; Fax: +1 617-525-2008; E-mail: deleaf@partners.org

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)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.

Results

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).

Conclusions

Bioavailable 25(OH)D could have a role as a biomarker or mediator of adverse outcomes among patients with established AKI.

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