Severe Vitamin D Deficiency as a Trigger for Metabolic Seizures in Infancy: A Case Series and a Comprehensive Review of the Literature.

Introduction: Hypocalcemia represents a major cause of seizures in children in the absence of fever or infections. Hypovitaminosis D, usually associated with a lack of proper prophylactic regimens, can trigger those events. This case series aims to highlight two cases of hypocalcemic seizures in infants, attributed to severe vitamin D deficiency, with the aim of raising awareness regarding the importance of vitamin D prophylaxis. A narrative review of the literature is also provided, which highlights similar reported cases. Methods: We hereby report two cases of male infants (aged 4 months and 5 months) who presented to the emergency department of a tertiary pediatric center with seizures in the absence of fever or infections. Diagnostic work-ups revealed low levels of total serum calcium and ionic calcium deficiency. The cause of the hypocalcemia turned out to be severe vitamin D deficiency in both cases, caused by complete absence of vitamin D supplements since birth and during maternal pregnancy. In both cases, combined oral calcium and vitamin D supplementation led to complete resolution of symptoms and restoration of normal calcium levels. A comprehensive review of the literature is also provided, which focuses on pediatric studies and case reports that analyzed the prevalence, particularities, and outcomes of hypocalcemic seizures related to vitamin D deficiency. Articles including subjects with congenital or endocrine disorders that could have caused hypocalcemia were ruled out. Results: After accessing the full-length form of each article and applying the inclusion and exclusion criteria, 27 articles were included, namely 14 studies and 13 case reports. Hypocalcemic seizures caused by vitamin D deficiency are more common in infants, are usually linked to maternal hypovitaminosis D, and have a higher prevalence in developing countries. Most of the case reports depicting hypocalcemic seizures were distinguished through very low vitamin D levels. Conclusions: These case series emphasize the importance of vitamin D supplementation for the prevention of hypocalcemia, which constitutes a major metabolic cause of seizures in infancy. Nevertheless, maternal vitamin D supplementation during pregnancy is the only factor that can ensure the presence of satisfactory deposits in the newborn and prevent hypovitaminosis D-related complications.