Low Vitamin D Levels May Make Sick Kids Sicker
Vitamin D deficiency is common among patients admitted to the pediatric intensive care unit (PICU) and is associated with more severe illness, two studies showed.
Among patients younger than 21 admitted to medical-surgical PICUs in Boston, 40.1% had deficient levels of 25-hydroxyvitamin D (25(OH)D), according to Kate Madden, MD, of Children's Hospital Boston, and colleagues.
Declining 25(OH)D levels were significantly associated with both worsening illness severity (P<0.001) and increasing vasopressor use (P=0.03), the researchers reported online ahead of the September issue of Pediatrics.
And in another study conducted at six Canadian PICUs, vitamin D deficiency was present in 69% of patients younger than 18 and was associated with worsening illness severity (P=0.005), according to James McNally, MD, PhD, of the Children's Hospital of Eastern Ontario in Ottawa, and colleagues.
The findings of both studies are consistent with prior research involving critically ill adults.
Madden and colleagues examined data on 511 patients (median age 5.3 years) admitted to the PICU over a 1-year period. The median serum level of 25(OH)D at admission was 22.5 ng/mL, and levels less than 20 ng/mL were considered deficient.
A lower likelihood of vitamin D deficiency was significantly associated with younger age, non-Hispanic white race, summer admission, use of supplemental vitamin D, and formula intake.
Illness severity was assessed using the Pediatric Risk of Mortality III (PRISM III) score.
For every 5-ng/mL decrease in 25(OH)D levels, the odds of moving up to the next PRISM III risk quartile increased by a relative 19% (OR 1.19, 95% CI 1.10 to 1.28). Patients with lower levels of 25(OH)D were also more likely to require vasopressors.
"The association between vitamin D level and both severity of illness and vasopressor use may be due to its role in innate immune function and inflammation, its role in calcium homeostasis, or influenced by fluid shifts and dilution," Madden and colleagues wrote.
McNally and colleagues, who derived similar results in Canadian PICUs, examined data from 326 children and teens (median age 3.7 years).
Their investigation was a secondary analysis of data and biological samples collected as part of the Adrenal Insufficiency in Pediatric Critical Illness Study (AIP).
Vitamin D deficiency was independently associated with an increase of 1.92 days spent in the PICU (P=0.03), in addition to higher PRISM III scores, with every additional point increasing the likelihood of being vitamin D deficient by 8% (P=0.005), they wrote.
McNally's group acknowledged some limitations, specifically that the AIP study was not intended to estimate the prevalence of vitamin D deficiency or designed to confer causality. Also, the AIP eligibility criteria may limit generalization because only those children sick enough to require central venous or arterial lines were enrolled.
Both groups called for studies testing whether aggressive vitamin D supplementation in the early stages of critical illness might improve clinical outcomes.
In terms of clinical implications, the results of the two studies "can be understood as supporting programs and interventions designed to prevent vitamin D deficiency," according to Steven Abrams, MD, and Jorge Coss-Bu, MD, of Texas Children's Hospital in Houston.
"What exactly this might entail is controversial, but, at a minimum, comprehensive efforts to ensure that children receive at least the recommended intake of vitamin D (400 IU/day for infants, 600 IU/day for children aged >1 year) should be developed and emphasized," they wrote in an accompanying editorial.
The studies "do not yet tell us the best way of assessing or treating low serum 25(OH)D levels in a PICU setting," they continued, "but point us to a program of public health and research on this topic, with clear identification of final outcomes and their clinical significance, focusing on both efficacy and safety of any proposed interventions."
The study by Madden and colleagues was supported by a grant from the Clinical Research Program at Children's Hospital Boston. Madden participated with support from Harvard Catalyst (an NIH award and financial contributions from Harvard University and its affiliated academic healthcare centers). One of her co-authors was supported in part by the Harvard Clinical and Translational Science Center.
Madden reported no conflicts of interest. One of her co-authors reported serving as a consultant for Diasorin Inc.
This study by McNally and colleagues was supported by the Canadian Institutes of Health Research and the Children's Hospital of Eastern Ontario Research Institute. Research fellowship funding to McNally was provided by the Children's Hospital of Eastern Ontario Popham Foundation.
McNally and colleagues reported no conflicts of interest.
Abrams and Coss-Bu reported no conflicts of interest.
Primary source: Pediatrics
Source reference:
Madden K, et al "Vitamin D deficiency in critically ill children" Pediatr 2012; DOI: 10.1542/peds.2011-3328.
Additional source: Pediatrics
Source reference:
McNally J, et al "The association of vitamin D status with pediatric critical illness" Pediatr 2012; DOI: 10.1542/peds.2011-3059.
Additional source: Pediatrics
Source reference:
Abrams S and Coss-Bu J "Vitamin D deficiency in critically ill children: a roadmap to interventional research" Pediatr 2012; DOI: 10.1542/peds.2012-1752.
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Todd Neale
Senior Staff Writer
Todd Neale, MedPage Today Staff Writer, got his start in journalism at Audubon Magazine and made a stop in directory publishing before landing at MedPage Today. He received a B.S. in biology from the University of Massachusetts Amherst and an M.A. in journalism from the Science, Health, and Environmental Reporting program at New York University.