Vitamin D toxicity from an unusual and unexpected source: a report of 2 cases

Introduction: Hypervitaminosis D is a relatively uncommon etiology of hypercalcemia. Toxicity is usually caused by very high doses, mostly secondary to erroneous prescription or administration of Vitamin D, and less commonly, contaminated foods or manufacturing errors of vitamin D-containing supplements. Case description: 16 year old male, previously healthy, presented with 2-week history of non specific symptoms (fatigue, gastrointestinal complaints). Investigations showed acute kidney injury and hypercalcemia (total calcium 3.81 mmol/L). Further diagnostic workup revealed markedly elevated 25-hydroxy-vitamin D levels (1910 nmol/L). He denied taking any vitamin D supplements; however, he reported consumption of creatine and protein supplements. Mass spectrometry analysis of the creatine supplement estimated a vitamin D content of 425,000 IU per serving (100 times the upper tolerable daily dose). A few months later, another previously healthy adolescent presented with severe hypercalcemia and acute kidney injury secondary to hypervitaminosis D. He was also using a creatine supplement from the same manufacturer brand and lot. Both patients were treated with IV hydration, calcitonin and pamidronate. They maintained normocalcemia after their initial presentation but required low-calcium diets and laboratory testing for months after this exposure. Discussion: We present 2 cases of hypervitaminosis D caused by a manufacturing error of a natural health product which did not claim to contain vitamin D. The use of dietary supplements is highly prevalent; their use should be incorporated in anamnesis and considered a potential source of toxicity when an alternative source cannot be found, regardless of the product label.