Vassiliou AG, et al. – In this retrospective observational cohort study, researchers evaluated the association of very low levels of 25-hydroxyvitamin D upon patient admission to the intensive care unit (ICU) with worse outcomes. Study participants included 227 initially non-septic, critically ill patients, in whom 25-hydroxyvitamin D was measured at ICU admission, as well as 192 healthy control participants. Patients were categorized according to their vitamin D levels at admission; the two patient groups were those with severely low 25-hydroxyvitamin D levels (< 7 ng/mL; n=101) and those with vitamin D levels ≥ 7 ng/mL (n=126). The investigators found that ICU admission 25-hydroxyvitamin D levels of critically ill patients were much lower vs those of healthy control participants. In addition, they found that sepsis development, increased risk of in-hospital mortality, or longer stay in the ICU were not predicted by severely low vitamin D levels (< 7 ng/mL) at ICU admission among critically ill patients. However, they noted an association of these severely low admission vitamin D levels in patients who will eventually develop sepsis with the development of respiratory tract infections.