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

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Author(s): Sara De Vincentis*, Antonino Russo, Marta Milazzo, Amedeo Lonardo, Maria Cristina De Santis, Vincenzo Rochira, Manuela Simoni, Bruno Madeo

Journal Name: Endocrine, Metabolic & Immune Disorders - Drug Targets
Formerly Current Drug Targets - Immune, Endocrine & Metabolic Disorders

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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.

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(E-pub Ahead of Print)
DOI: 10.2174/1871530320666201007152230
Price: $95

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