Rationale: Acute lower respiratory infection (ALRI) is one of the most common reasons for hospitalization and intensive care unit admission among children. Season related decreases in the immunomodulatory molecule, vitamin D, remain an unexplored factor that might contribute to the increased occurrence of ALRI in children.
Objective: To investigate a possible association between vitamin D deficiency and respiratory infection by comparing serum 25 hydroxyvitamin D [25(OH)D] levels in a group of young children with ALRI to an age-matched group without respiratory infection.
Patients and methods: Participants with a diagnosis of bronchiolitis or pneumonia (n = 55 or 50, respectively), as well as control subjects without respiratory symptoms (n = 92), were recruited at the Royal University Hospital, Saskatoon, Saskatchewan, Canada from November 2007 to May 2008. 25(OH)D levels were measured in patient serum using a competitive enzyme linked immunoassay.
Results: The mean vitamin D level for the entire ALRI group was not significantly different from the control group (81 +/- 40 vs. 83 +/- 30 nmol/L, respectively). The mean vitamin D level for the ALRI subjects admitted to the pediatric intensive care unit (49 +/- 24 nmol/L) was significantly lower than that observed for both control (83 +/- 30 nmol/L) and ALRI subjects admitted to the general pediatrics ward (87 +/- 39 nmol/L). Vitamin D deficiency remained statistically related to pediatric intensive care unit admission in the multivariate analysis.
Conclusion: No difference was observed in vitamin D levels between the entire ALRI group and control groups; however, significantly more children admitted to the pediatric intensive care unit with ALRI were vitamin D deficient. These findings suggest that the immunomodulatory properties of vitamin D might influence ALRI disease severity.