Defining Vitamin D Deficiency in Children: Beyond 25-OH Vitamin D Serum Concentrations

It is generally accepted that of the circulating vitamin D metabolites, serum 25-OH vitamin D (25[OH]D) measurements best reflect clinical vitamin D status. In this issue of Pediatrics , Mansbach et al1 address this issue, namely, what serum levels of 25(OH)D in infants and children should be used to define vitamin D sufficiency and deficiency states? Using the 2001–2006 National Health and Nutrition Examination Survey's cross-sectional surveys of 25(OH)D serum concentrations in a presumed healthy population of 4558 US children between ages 1 and 11 years, the authors estimate that 320000 US children (95% confidence interval [CI]: 220000–430000) have 25(OH)D levels at <25 nmol/L, 6.3 million children (95% CI: 5.4–7.2 million) have levels at <50 nmol/L, and 24 million children (95% CI: 21–26 million) have levels at <75 nmol/L. Not unexpectedly, the lowest mean values were found in black children, nearly all of whom had levels of <75 nmol/L. If one approximates the total population of US children between 1 and 11 years of age as 40 million,2 the estimated prevalence of 25(OH)D levels of <75 nmol/L would be 60%, and the estimated prevalence with levels of <50 nmol/L would be 16%. Relatively few children (1%) would have serum levels of <27.5 nmol/L, the value used to define the level of deficiency in a 1997 Institute of Medicine (IOM) report.3 However, if one uses a cut-off value of <50 nmol/L, as recently suggested by the American Academy of Pediatrics, then this article raises the issue that … Address correspondence to Frank R. Greer, MD, Meritor Hospital, Perinatal Center, 202 S Park St, Madison, WI 53715. E-mail: frgreer{at}pediatrics.wisc.edu