1,25-Dihydroxyvitamin D Levels in Pediatric Intensive Care Units: Risk Factors and Association With Clinical Course

Abstract

Multiple adult and some pediatric critical care studies have suggested that poor vitamin D status is associated with illness severity and outcome. The majority have evaluated vitamin D status through serum 25-hydroxyvitamin D [25(OH)D]. Critical illness-related organ dysfunction may result in impaired conversion of 25(OH)D to the active hormone 1,25-dihydroxyvitamin D [1,25(OH)2D]. Consequently 1,25(OH)2D levels could be an independent additive prognostic marker in the intensive care unit. The distribution of 1,25(OH)2D levels, prevalence of low levels, investigation of risk factors, and tests for associations with markers of illness severity and outcome are reported. This was a secondary analysis of data and samples collected as part of a prospective cohort study in six Canadian pediatric intensive care units (PICUs). Admission blood 1,25(OH)2D concentrations were measured. The median cohort 1,25(OH)2D level was 93.3 pmol/L (interquartile range, 53.0-121.9) with 13% (95% confidence interval, 9-17) and 21% (95% confidence interval, 17-27) of patients having levels of <40 and <50 pmol/L, respectively. Low 1,25(OH)2D levels occurred more often in patients with low 25(OH)D and hepatic, renal, and parathyroid organ dysfunction. After adjustment for 25(OH)D, low 1,25(OH)2D levels were not associated with catecholamine or fluid administration, ventilation, PICU length of stay, or mortality. Critically ill children are at risk for low 1,25(OH)2D levels, particularly in the presence of established risk factors. However, the lack of association between the 1,25(OH)2D level and selected outcome measures, after controlling for 25(OH)D, does not suggest value in measuring this metabolite at the time of PICU admission.