Endocrine Abstracts

Multiple fractures, for which there is no clear explanation, raise the possibility of non-accidental injury (NAI). Vitamin D deficiency, defined as serum 25-hydroxyvitamin D (25OHD) concentrations of <50 nmol/l, is common during pregnancy and infancy.

It had been suggested by Keller & Barnes (Pediatr Radiol 2008 38 1210–1216) that subclinical vitamin D deficiency could explain some fractures that have been ascribed to NAI. Evidence from review of available literature (observational studies and series of case reports), suggests that children with clinical, biochemical and radiological evidence of rickets have increased risk of fracture. In a retrospective study, Chapman et al found that fractures 17.5% of infants and toddlers with rickets aged between 2 and 14 months (Pediatr Radiol 2010 40(7) 1184–1189). Fractures only occurred in those who were mobile and had severe radiological evidence of rickets. None of the fractures were considered to be characteristic of NAI. In contrast, there is no convincing evidence that subclinical vitamin D deficiency is associated with increased fracture risk in children. Schilling and colleagues found that serum 25OHD levels in 118 <2-year-old infants with fractures which were considered to have occurred accidentally (60%) or due to non-accidental injury (31%) or where the cause could not be determined with certainty (9%) were not different (Pediatrics 2011 127(5) 835–841).

In infants with multiple unexplained fractures the possibility of NAI and disorders associated with fragility fractures, e.g. osteogenesis imperfecta and florid vitamin D deficiency rickets should be considered. However, vitamin D deficiency, in the absence of biochemical & radiological evidence of rickets is not likely to be associated with increase risk of fragility fractures in young infants.