What is the treatment for elevated vitamin D (hypercalcemia)?

Treatment of Vitamin D Toxicity (Hypercalcemia)

The treatment for vitamin D toxicity causing hypercalcemia includes immediate discontinuation of vitamin D supplementation, aggressive intravenous hydration, and in severe cases, bisphosphonate therapy such as pamidronate, which effectively reduces hypercalcemia by decreasing bone resorption. 1, 2

Clinical Presentation and Diagnosis

• Vitamin D toxicity typically presents with symptoms related to hypercalcemia including nausea, vomiting, muscle weakness, fatigue, gastrointestinal complaints, and in severe cases, acute kidney injury 1, 3
• Diagnosis is confirmed by finding elevated serum calcium levels (>10.2 mg/dL) along with markedly elevated 25-hydroxyvitamin D levels (typically >150 ng/mL or >375 nmol/L) 1, 3
• Acute kidney injury is a common complication due to hypercalcemia-induced renal vasoconstriction and calcium deposition in renal tubules 1, 3

First-Line Treatment Approach

• Immediately discontinue all vitamin D supplements, calcium supplements, and vitamin D-fortified foods 1, 2
• Initiate aggressive intravenous hydration with normal saline to promote calcium excretion 2
• Monitor serum calcium, phosphorus, and renal function every 2-3 days initially, then weekly until stable 4
• Implement a low-calcium diet until calcium levels normalize 3

Pharmacological Management

• For severe hypercalcemia (>12 mg/dL) or symptomatic patients:

  • Administer bisphosphonates, particularly pamidronate, which has been shown to rapidly reduce calcium levels by inhibiting bone resorption 2
  • Consider calcitonin for short-term management of severe hypercalcemia while waiting for bisphosphonates to take effect 3
  • Glucocorticoids may be used as they reduce intestinal calcium absorption and inhibit 1-alpha-hydroxylation of vitamin D, though their effect is less rapid than bisphosphonates 5, 2

• For moderate hypercalcemia:

  • Loop diuretics (e.g., furosemide) may be considered after adequate hydration to enhance calcium excretion, but should be used cautiously to avoid dehydration 4

Monitoring and Follow-up

• Measure serum calcium and phosphorus levels every 2-3 days initially, then weekly until stable 4
• Monitor renal function closely as acute kidney injury is common 1, 3
• Be aware that vitamin D has a long half-life, and hypercalcemia may persist for weeks to months despite treatment 1
• Regular follow-up is essential as normalization of 25-hydroxyvitamin D levels may take up to 18 months in severe cases 1

Prevention of Recurrence

• Educate patients about appropriate vitamin D dosing - the safety upper limit is generally considered to be 4,000 IU/day 6
• Caution patients about over-the-counter supplements that may contain vitamin D, even if not listed on the label 3
• For patients requiring vitamin D supplementation after recovery, use conservative doses (800-1,000 IU/day) with regular monitoring 6
• Avoid intermittent high-dose vitamin D regimens as they may increase risk of toxicity 6

Important Caveats

• Vitamin D toxicity is rare with standard supplementation doses but can occur with excessive intake (typically >50,000 IU/day for extended periods) 1, 6
• Unexpected sources of vitamin D toxicity include manufacturing errors in supplements and contaminated foods 3
• Recovery from vitamin D toxicity may be prolonged - renal function typically normalizes within 6 months, but vitamin D levels may remain elevated for up to 18 months 1
• Patients may require ongoing low-calcium diets and monitoring for several months after initial treatment 3