Vitamin D in critically ill patients
The pleiotropic functions of vitamin D, the clinical impact of deficiency and effect of supplementation have been a research focus in many specialties of ambulatory medicine. However, its prevalence in critical illness was not known. The parathyroid-vitamin D- calcium axis is the only endocrine axis that had not been previously described in critically ill patients. To study the effects of correction of deficiency, the dose, route and method of vitamin D supplementation needed investigation.
... ically ill patients are heterogeneous and response to supplementation may not be consistent in all cohorts. This information is key to inform the design of a randomised controlled trial of supplementation. This thesis was a program of research that included a prospective observational study to describe serial changes in the parathyroid-vitamin D-calcium axis and the association with clinical outcomes in a sample of critically ill patients. This was followed by a randomised trial comparing two doses of intramuscular vitamin D to study the effectiveness and safety of supplementation. Subsequently, a sample of patients requiring life-sustaining extracorporeal support (ECMO) was studied to study pharmacokinetic profiles of vitamin D in patients with extreme disease severity. The observational study found marked changes in the parathyroid-vitamin D-calcium axis, which was associated with adverse outcomes. The supplementation study showed that a single intramuscular injection of cholecalciferol corrected vitamin D deficiency safely in critically ill patients. Vitamin D repletion was accompanied by a reduction in pro-inflammatory responses. The study on ECMO patients found them to be almost universally deficient in vitamin D. Supplementation by the single intramuscular dose corrected deficiency in only half these patients. Vitamin D deficiency is common in critical illness and is associated with adverse outcomes. Supplementation can be achieved effectively and safely in most patients. Groups of critically ill patients, such as th [...]