Vitamin D deficiency in critically ill adults

Introduction. In the last few decades, many new findings have shed light on the role of vitamin D in a number of diseases. Currently, vitamin D deficiency is discussed as a modifiable risk factor for morbidity and mortality in critically ill patients. The aim of this paper is to give a structured overview on the currently available literature in this field and to detect knowledge gaps. Methods. A literature study was performed. Relevant medical literature was searched mainly through the online database PubMed. Results. The literature research retrieved 30 observational studies in an intensive care unit (ICU) setting, four observational studies in paediatric ICUs and nine observational studies in a non-ICU-setting. Since 2003, nine randomized controlled trials (RCTs) on vitamin D supplementation in critically ill adults have been carried out in Austria, Belgium, Australia and the USA. The number of participants varied from 25 to 475 (716 in total). The odds ratio (OR) in these RCTs for mortality was calculated between 0.69 and 1.17 (0.70 in total). Discussion and Conclusion. Vitamin D deficiency in critically ill patients is very common and associated with a poor outcome. Previous studies have shown promising data about a potential benefit of high-dose vitamin D substitution in this vulnerable group. However, the studies and results are heterogeneous, and therefore insufficient to prove a causal relation. Large phase III interventional trials are necessary to confirm the assumed beneficial effects of vitamin D substitution in critical illness. © Springer-Verlag GmbH Austria 2017.