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A possible genetic defect in 25-hydroxylation as a cause of rickets
S J Casella1, B J Reiner, T C Chen
1Division of Pediatric Endocrinology, Johns Hopkins University School of Medicine, Baltimore, Maryland.
Abstract:
We examined two siblings who had severe rickets at ages 2 and 7 years, respectively, despite a history of adequate vitamin D intake. The patients' sera had calcium concentrations at the lower limits of normal, low phosphate concentrations, elevated alkaline phosphatase activity, and low levels of 25-hydroxyvitamin D. Treatment with high doses of vitamin D2 resulted in resolution of the biochemical abnormalities and radiographic deformities; pharmacologic doses of vitamin D2 were required to maintain normal concentrations of 25-hydroxyvitamin D in the serum even though vitamin D absorption was normal. These children may have a genetic defect of the 25-hydroxylation step in vitamin D activation.
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