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How Much Vitamin D is Too Much? A Case Report and Review of the Literature

Author(s):

Sara De Vincentis*, Antonino Russo, Marta Milazzo, Amedeo Lonardo, Maria Cristina De Santis, Vincenzo Rochira, Manuela Simoni and Bruno Madeo   Pages 1 - 7 ( 7 )

Abstract:


Background: The beneficial effects of vitamin D, together with the high prevalence of vitamin D deficiency, have led to an expanding use of vitamin D analogues. While inappropriate consumption is a recognized cause of harm, definition of doses at which vitamin D becomes toxic remain elusive.

Case presentation: A 56-year woman was admitted to our Hospital following a 3-week history of nausea, vomiting and muscle weakness. The patient had been assuming very high dose of cholecalciferol since 20 months (cumulative 78,000,000UI, mean daily 130,000UI), as indicated by a non-conventional protocol for multiple sclerosis. Before starting vitamin D integration, serum calcium and phosphorus levels were normal, while 25OH-vitamin D levels were very low (12.25 nmol/L). On admission, hypercalcemia (3.23 mmol/L) and acute kidney injury (eGFR 20 mL/min) were detected, associated with high concentrations of 25OH-vitamin D (920 nmol/L), confirming the suspicion of vitamin D intoxication. Vitamin D integration was stopped and, in a week, hypercalcemia normalized. It took about 6 months for renal function and 18 months for vitamin D values to go back to normal.

Conclusions: This case confirms that vitamin D intoxication is possible albeit with a really high dose. The doses used in clinical practice are far lower than these and, therefore, intoxication rarely occurs even in those individuals whose baseline vitamin D serum levels have never been assessed. Repeated measurements of vitamin D are not necessary in patients under standard integrative therapy. However, patients and clinicians should be aware of the potential dangers of vitamin D overdose.

Keywords:

Vitamin D, intoxication, overdose, cholecalciferol, toxicity, hypercalcemia.

Affiliation:

Unit of Endocrinology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Unit of Endocrinology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Unit of Metabolic Medicine, Azienda Ospedaliero- Universitaria di Modena, Modena, Unit of Metabolic Medicine, Azienda Ospedaliero- Universitaria di Modena, Modena, Department of Laboratory Medicine and Pathology, Azienda USL of Modena, Unit of Endocrinology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Unit of Endocrinology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Unit of Endocrinology, Department of Medical Specialties, Azienda Ospedaliero-Universitaria di Modena, Ospedale Civile di Baggiovara, Modena



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