Vitamin D in critically ill patients.

Vitamin D deficiency is a commonly observed global phenomenon, both in the general population and in hospitalized patients, including critically ill patients. Vitamin D deficiency is associated with multiple adverse health outcomes, including increased morbidity and mortality in the general population and in critically ill patients. Vitamin D is a fatsoluble vitamin that plays an important role in bone metabolism. However, Vitamin D is also a steroid hormone that exerts multiple pleiotropic effects. Vitamin D regulates immunity, inflammation, cell proliferation, differentiation, apoptosis, and angiogenesis. There is growing evidence of a close relationship between vitamin D insufficiency and various systemic disorders, i.e., type II diabetes, certain types of cancer, obesity, and cardiovascular morbidities. The purpose of this article is to present the current knowledge on the relationship between vitamin D status and critical illness.