What is the treatment for vitamin D toxicity?

Treatment for Vitamin D Toxicity

The treatment of vitamin D toxicity should focus on discontinuation of vitamin D supplementation, low calcium diet, intravenous hydration with saline, and may require additional pharmacological interventions including loop diuretics, glucocorticoids, calcitonin, and bisphosphonates in severe cases. 1

Diagnosis of Vitamin D Toxicity

Vitamin D toxicity is characterized by:

• Serum 25(OH)D levels above 150 ng/ml (375 nmol/L) 2, 1
• Hypercalcemia (often >11 mg/dL)
• Normal or high serum phosphorus levels
• Normal or low levels of alkaline phosphatase (ALP)
• Low serum parathyroid hormone (PTH)
• High urine calcium/creatinine ratio 1

Clinical manifestations may include:

• Generalized symptoms: fatigue, weakness
• Neurological symptoms: altered mental status, irritability, confusion, coma
• Gastrointestinal symptoms: nausea, vomiting, constipation
• Endocrinological symptoms: polyuria, polydipsia
• Renal complications: kidney stones, acute kidney injury 2, 1, 3

Treatment Algorithm

Step 1: Immediate Interventions

• Discontinue all vitamin D supplements 1
• Implement low calcium and phosphorus diet 1
• Begin intravenous hydration with normal saline to promote calcium excretion 1, 4

Step 2: Pharmacological Management

For severe hypercalcemia (>14 mg/dL) or symptomatic patients:

• Loop diuretics (e.g., furosemide) after adequate hydration to enhance calcium excretion 1, 4
• Glucocorticoids (e.g., prednisone) to decrease intestinal calcium absorption and reduce 1,25(OH)₂D production 1, 4
• Calcitonin for rapid but short-term reduction of calcium levels 1
• Bisphosphonates for persistent hypercalcemia 1

Step 3: Monitoring and Follow-up

• Monitor serum calcium, phosphorus, creatinine, and 25(OH)D levels regularly
• Continue treatment until normocalcemia is achieved
• Be aware that effects may persist for months due to vitamin D storage in adipose tissue 1

Special Considerations

Severity Assessment

Emergency intervention is necessary when calcium concentration exceeds 14 mg/dL due to potential adverse effects on cardiac, central nervous system, renal, and gastrointestinal functions 1.

Duration of Treatment

Since vitamin D is stored in fat tissues, effects of toxicity may last for months despite removal of the exogenous source of vitamin D 1. Treatment may need to be continued for extended periods.

Common Causes of Vitamin D Toxicity

Vitamin D toxicity is typically iatrogenic, resulting from:

• Prescription of mega-doses of vitamin D (often 50,000 IU or more weekly) 3
• Manufacturing errors in supplements 2
• Overzealous correction of vitamin D deficiency 3
• Quality control issues with over-the-counter supplements 5

Prevention of Vitamin D Toxicity

To prevent vitamin D toxicity:

• Adhere to safe upper limits of vitamin D intake (generally 4,000 IU/day for adults) 2, 6
• Check serum 25(OH)D levels before initiating high-dose vitamin D therapy 1
• Question patients about previous vitamin D administration and supplement use 1
• Monitor serum calcium and 25(OH)D levels during high-dose supplementation 6
• Avoid ultra-high single loading doses (>300,000 IU) 2

By following this treatment approach and implementing preventive measures, the potentially serious consequences of vitamin D toxicity can be effectively managed and prevented.