Background: Hypocalcemia is one of the most common disorders of metabolism in children. One of the most known causes is hypovitaminosis D, an extremely widespread condition in the world, both in developed and developing countries. Etiology is related to poor exposure to sunlight and inadequate diet, especially in subjects with dark skin or exclusively breastfed or born to mothers with vitamin D deficiency by ethnic and cultural reasons. Case Presentation: We report a case of a teenager from Morocco, who presented a tetanic crisis in the course of influenza B. The laboratory tests showed severe hypocalcemia and low serum vitamin D concentration with increased parathyroid hormone value. The administration of calcium and vitamin D normalized the clinical and laboratory parameters. Conclusions: Adolescents of ethnic groups at risk frequently find themselves in a chronic situation of altered metabolism deriving from vitamin D deficiency. Hence, a simple insult, as influenza B virus, can lead to severe pathological manifestations.

Keywords: Hypovitaminosis D risk factors, hypocalcemia, influenza B, adolescent, case report