Increased blood 1,25 dihydroxyvitamin D levels in infants with Metabolic Bone Disease of Infancy in contested cases of child abuse.

Purpose: Metabolic Bone Disease of Infancy (MBDI) is a multifactorial disorder of bone fragility that presents with multiple unexplained fractures (MUF) and is often misdiagnosed as child abuse. The diagnosis of MBDI is made by the finding of radiographic features of healing rickets and risk factors for MBDI. Our anecdotal experience indicates blood 1,25-dihydroxyvitamin D (1,25-DiOHVD) is sometimes elevated. The purpose of this retrospective study was to review cases of MBDI in which child abuse was alleged and the alleged perpetrator denied wrongdoing. Methods: We reviewed forensic cases of MBDI born between 2015 and 2021. The diagnosis was based on radiographic findings of healing rickets. Records were reviewed for blood 1,25-DiOHVD testing. Results: 22 of the 76 infants (29 %) had a blood 1,25-DiOHVD level performed at the time of presentation with fractures. The average age of presentation with fractures was 11 weeks.3 of the 22 infants (14 %) had a normal 1,25-DiOHVD blood level, and 19 of the 22 infants (86 %) had an elevated level. None had low levels. Conclusion: Blood 1,25-DiOHVD is often elevated in infants with MBDI. Elevated blood 1,25-DiOHVD levels cause increased bone resorption and decreased bone mineralization, and thus this finding is not unexpected since all infants had evidence of healing rickets on imaging studies. These results indicate blood 1,25-DiOHVD should be done in contested cases of child abuse in infants with MUF as an elevated level indicates bone fragility.