From the Guidelines
Hypervitaminosis D is a condition that requires immediate medical attention, and treatment involves stopping all vitamin D supplements and limiting dietary sources of vitamin D, as well as medical management with intravenous fluids, loop diuretics, and corticosteroids as needed, as recommended by the U.S. Preventive Services Task Force 1.
Causes and Symptoms
Hypervitaminosis D occurs when there is an excessive intake of vitamin D, leading to toxic levels in the body. This can cause a range of symptoms, including nausea, vomiting, weakness, confusion, kidney problems, and in severe cases, cardiac arrhythmias. The condition is characterized by hypercalcemia, hyperphosphatemia, suppressed parathyroid hormone, and hypercalciuria.
Treatment and Management
Treatment for hypervitaminosis D involves immediately stopping all vitamin D supplements and limiting dietary sources of vitamin D. Patients should also avoid sun exposure and reduce calcium intake. Medical management includes:
- Intravenous fluids to promote calcium excretion
- Loop diuretics like furosemide (20-40mg twice daily) to increase urinary calcium elimination
- Corticosteroids such as prednisone (20-40mg daily for 1-2 weeks) to decrease intestinal calcium absorption
- Bisphosphonates like pamidronate (60-90mg IV) may be used for significant hypercalcemia
Monitoring and Follow-up
Regular monitoring of serum calcium, phosphorus, and vitamin D levels is essential during treatment, which typically continues until calcium levels normalize, usually within days to weeks depending on severity. It is also important to note that the 25-(OH)D level associated with toxicity is often defined as >500 nmol/L [>200 ng/mL] 1.
Key Considerations
- The U.S. Preventive Services Task Force recommends against routine screening for vitamin D deficiency in adults, as the current evidence is inadequate to determine whether screening and treatment improve clinical outcomes 1.
- Treatment with oral vitamin D may be associated with increased risk for kidney stones, and treatment with increased sun exposure may increase risk for skin cancer 1.
From the Research
Definition and Causes of Hypervitaminosis D
- Hypervitaminosis D is a relatively uncommon etiology of hypercalcemia, usually caused by very high doses of vitamin D, mostly secondary to erroneous prescription or administration of vitamin D, and less commonly, contaminated foods or manufacturing errors of vitamin D-containing supplements 2.
- The use of dietary supplements is highly prevalent and should be considered a potential source of toxicity when an alternative source cannot be found, regardless of the product label 2.
- Vitamin D deficiency is highly prevalent, and there are an increasing number of reports of vitamin D toxicity, mostly related to the misuse of over-the-counter supplements 3.
Symptoms and Diagnosis
- Symptoms of hypervitaminosis D can include nonspecific symptoms such as fatigue, gastrointestinal complaints, acute kidney injury, and hypercalcemia 2.
- Investigations may show markedly elevated 25-hydroxyvitamin D levels, and mass spectrometry analysis of supplements can estimate vitamin D content 2.
- Biochemical markers of vitamin D toxicity, such as hypervitaminosis D and hypercalcemia, can be assessed to determine the risk of toxicity 4.
Treatment and Prevention
- Treatment of hypervitaminosis D-induced hypercalcaemia may involve glucocorticoids and bisphosphonates, in addition to calcitonin and intravenous fluids 5.
- Patients with hypervitaminosis D may require low-calcium diets and laboratory testing for months after exposure 2.
- Regulation of over-the-counter medications by the Food and Drug Administration could help prevent incidental toxicity 3.
- Prolonged consumption of vitamin D supplementation may induce hypercalcemia, hypercalciuria, and hyperphosphatemia, which are considered initial signs of vitamin D intoxication, even without developing hypervitaminosis D 6.