Calciferol Deficiency Mimicking Abusive Fractures in Infants: Is There Any Evidence?

Abstract

T he history of calciferol metabolism and biochemistry is tightly intertwined with that of American pediatrics. Rickets was a widespread affliction of children in urban areas in the 19th and early 20th centuries. Mellanby recognized the anti-rachitic properties of a fat-soluble substance that was incorrectly named ‘‘vitamin’’ D. Shortly thereafter, Eliot undertook a seminal clinical trial in New Haven that demonstrated the ability of cod-liver oil to prevent rickets in infants. Within decades, supplementation of nursing infants became nearly universal, and clinical rickets largely disappeared. In the latter part of the 20th century, lax prescribing of calciferol supplements to nursing children, combined with an increasing number of mothers of darkly pigmented infants choosing to breast feed, led to a resurgence of clinical rickets. Because we are well into the 21st century, clinical rickets in infants again is largely disappearing. As this has happened, there has been an increasing interest in the possibility that degrees of calciferol deficiency insufficient to cause frank rickets could still have deleterious skeletal effects. This interest has been informed by recent information in adults suggesting that levels of calciferol (as assessed by 25hydroxycholecalciferol [25(OH)D]) we have previously considered normal may actually be low. This, in turn, has led to the suggestion that mild degrees of calciferol deficiency, in the absence of actual rickets, could predispose the infant to fractures. It is sometimes argued that such subclinical calciferol deficiency could explain some fractures that have been ascribed to abuse. Multiple longbone fractures have long been recognized as an indicator for child abuse. The implications for the child when fractures caused by abuse aremistakenly attributed to fractures caused by rickets are potentially life-threatening. Similarly, misdiagnosis of abuse in the setting of clinical rickets has significant legal, social, emotional, and clinical implications. In this commentary, we will provide a review of our current understanding of the metabolism of calciferol in infants. We will then discuss recent data defining normal levels of calciferol at various ages, including in infants. We will examine the fracture risk associated with actual clinical rickets and the evidence that this risk is present with milder degrees of calciferol deficiency. Lastly, we will consider the proposition that mild degrees of calciferol deficiency can predispose infants to fractures mimicking those caused by non-accidental trauma of infants.