The Relationship Between Vitamin D Status and Adrenal Insufficiency in Critically Ill Children

Context: Recent studies in critically ill populations have suggested both adrenal insufficiency (AI) and vitamin D deficiency to be associated with worse clinical outcome. There are multiple mechanisms through which these pleiotropic hormones might synergistically influence critical illness. Objective: The aim of the study was to investigate potential relationships between vitamin D status, adrenal status, and cardiovascular dysfunction in critically ill children. Design: We conducted a secondary analysis of data from a prospective cohort study. Setting and Patients: The study was conducted on 319 children admitted to 6 Canadian tertiary-care pediatric intensive care units. Main Outcome Measures: Vitamin D status was determined through total 25-hydroxyvitamin D (25OHD) levels. AI was defined as a cortisol increment under 9 μg/dL after low-dose cosyntropin. Clinically significant cardiovascular dysfunction was defined as catecholamine requirement during pediatric intensive care unit admission. Results: Using 3 different thresholds to define vitamin D deficiency, no association was found between vitamin D status and AI. Furthermore, linear regression failed to identify a relationship between 25OHD and baseline or post-cosyntropin cortisol. However, the association between AI and cardiovascular dysfunction was influenced by vitamin D status; compared to children with 25OHD above 30 nmol/L, AI in the vitamin D-deficient group was associated with significantly higher odds of catecholamine use (odds ratio, 5.29 vs 1.63; P = .046). Conclusions: We did not find evidence of a direct association between vitamin D status and critical illness-related AI. However, our results do suggest that vitamin D deficiency exacerbates the effect of AI on cardiovascular stability in critically ill children.