Critically Ill Children Have Low Vitamin D-Binding Protein, Influencing Bioavailability of Vitamin D.

Rationale: Vitamin D deficiency, often defined by total serum 25-hydroxyvitamin D (25[OH]D) <20 ng/ml, is common in critically ill patients, with associations with increased mortality and morbidity in the intensive care unit. Correction of vitamin D deficiency in critical illness has been recommended, and ongoing clinical trials are investigating the effect of repletion on patient outcome. The biologically active amount of 25(OH)D depends on the concentration and protein isoform of vitamin D–binding protein (VDBP), which is also an acute-phase reactant affected by inflammation and injury.Objectives: We performed a secondary analysis of a cohort of critically ill children in which we reported a high rate of vitamin D deficiency, to examine how VDBP level and genotype would impact vitamin D status.Methods: We prospectively enrolled 511 children admitted to the pediatric intensive care unit over a 12-month period.Measurements and Main Results: We measured serum VDBP in 479 children. We genotyped single nucle...