Recent neonatal hypercalcaemia and congenital hypothyroidism cases have sparked a review of vitamin D and iodine containing supplements for pregnant women. Nutrivigilance, a nutritional monitoring system utilised by ANSES, identified five cases of neonatal hypercalcemia and two of congenital hypothyroidism likely to have arisen from maternal consumption of food supplements.
Although two instances of hypercalcemia are attributed to genetic vitamin D hypersensitivity, “except in one case, the dietary supplement was not the only source of vitamin D,” the study stated.
“Similarly, for the case of hypothyroidism related to an iodized overload, the dietary supplement was not the sole source of iodine,” the agency added.
ANSES proposes a number of measures in the report designed to prevent such cases in future.
In hypercalcemia cases, this includes testing the child for mutation of the cyp24A1 gene, and either withdrawing or closely monitoring vitamin D supplementation, depending on whether any mutation is homo- or heterozygous respectively.
In the case of iodine overload, the Agency recommends, “Simultaneous exposure to multiple sources of iodine should be avoided during pregnancy because it may increase the risk of neonatal hypothyroidism. Pregnant women should report to their doctor or midwife any product (Medicinal product or food supplement) taken in self-medication or prescribed by another health professional.”