Title:How Much Vitamin D is Too Much? A Case Report and Review of the Literature
Volume: 21
Issue: 9
Author(s): Sara De Vincentis*, Antonino Russo, Marta Milazzo, Amedeo Lonardo, Maria C. De Santis, Vincenzo Rochira, Manuela Simoni and Bruno Madeo
Affiliation:
- Unit of Endocrinology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena,Italy
Keywords:
Vitamin D, intoxication, overdose, cholecalciferol, toxicity, hypercalcemia.
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, the determination of doses at which vitamin D becomes
toxic remains 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 a very high dose of cholecalciferol
for 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.
Conclusion: This case confirms that vitamin D intoxication is possible, albeit with a 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 for patients under standard integrative therapy.
However, patients and clinicians should be aware of the potential dangers of vitamin D overdose.
