Fractures are uncommon in young, nonambulatory infants. The differential diagnosis includes nonaccidental injury (NAI) and
metabolic bone disease, including
rickets. While
rickets typically present after six months of age, multiple cases have been reported in younger infants. We report a case of an 11-week-old male infant who presented with a
spiral fracture of the humerus and no radiologic evidence of
rickets. A detailed psychosocial assessment failed to reveal any risk factors for NAI. The patient had elevated
alkaline phosphatase and PTH with low 25 hydroxyvitamin D and 1,25 dihydroxyvitamin D levels. Additionally, the mother was noncompliant with prenatal
vitamins, exclusively breastfeeding without
vitamin D supplementation, and had markedly low
vitamin D levels 15 weeks postpartum. The biochemical data and history were consistent with
rickets. Given the diagnostic dilemma, the working diagnosis was
rickets and the patient was started on
ergocalciferol with subsequent normalization of his laboratory values and healing of the fracture. These findings are consistent with nutritional
rickets largely due to maternal-fetal hypovitaminosis D. This case highlights that in young infants
rickets should be considered even in the absence of positive radiologic findings. Additionally, it illustrates the importance of maintaining adequate
vitamin D supplementation during pregnancy and early infancy.