What is the treatment for vitamin D toxicity?

Treatment for Vitamin D Toxicity

The treatment for vitamin D toxicity requires immediate discontinuation of all vitamin D supplements, implementation of a low calcium diet, intravenous hydration with saline, and may require additional pharmacological interventions such as loop diuretics, glucocorticoids, calcitonin, and bisphosphonates depending on the severity of hypercalcemia. 1

Clinical Presentation and Diagnosis

Vitamin D toxicity is characterized by:

• Hypercalcemia (often >11 mg/dL, severe when >14 mg/dL)
• Elevated serum 25(OH)D levels (typically >150 ng/ml or >375 nmol/L) 2
• Normal or low parathyroid hormone (PTH) levels
• High urine calcium/creatinine ratio
• Normal or high serum phosphorus levels
• Normal or low alkaline phosphatase levels 1

Symptoms may include:

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

Treatment Algorithm

For Severe Hypercalcemia (>14 mg/dL) - Emergency Intervention Required:

1. Immediate discontinuation of all vitamin D supplements 1

2. Aggressive intravenous hydration:

   • Normal saline (0.9% NaCl) at 200-300 mL/hour initially
   • Goal: restore intravascular volume and enhance calcium excretion 1, 3

3. Loop diuretics (after adequate hydration):

   • Furosemide 20-40 mg IV every 2-4 hours
   • Enhances calcium excretion 1, 3

4. Glucocorticoids:

   • Prednisone 20-40 mg/day orally
   • Reduces intestinal calcium absorption and may decrease 1,25(OH)2D production 1, 3

5. Calcitonin:

   • 4-8 IU/kg subcutaneously or intramuscularly every 12 hours
   • Provides rapid but short-term reduction in serum calcium 1, 4

6. Bisphosphonates (for persistent hypercalcemia):

   • Pamidronate 60-90 mg IV over 2-4 hours
   • Inhibits bone resorption 1, 4

For Moderate Hypercalcemia (11-14 mg/dL):

1. Discontinue vitamin D supplements 1

2. Oral or IV hydration based on clinical status

3. Low calcium and phosphorus diet 1

4. Monitor serum calcium, phosphorus, and renal function every 1-3 days until stable

Important Considerations

• Effects of vitamin D toxicity may persist for months after discontinuation due to storage in adipose tissue 1

• Regular monitoring is essential as normalization of calcium levels may take weeks to months 4

• Patients may require a low-calcium diet and regular laboratory testing for several months after initial treatment 4

• Kidney function should be closely monitored as acute kidney injury is a common complication 4, 5

Common Pitfalls and Caveats

1. Failure to identify the source: Vitamin D toxicity can result from:

   • Prescription errors (most common) 5
   • Manufacturing errors in supplements 4
   • Contaminated foods 4
   • Unlabeled vitamin D in supplements 4

2. Delayed diagnosis: Always consider vitamin D toxicity in patients with unexplained hypercalcemia, especially those with recent supplement use 5

3. Inadequate duration of follow-up: Effects can persist for months due to fat storage of vitamin D 1

4. Overlooking supplement use: Always question patients about all supplements, not just those labeled as containing vitamin D 4

5. Misdiagnosis of vitamin D deficiency: Treating presumed deficiency without checking 25(OH)D levels can lead to toxicity 1

6. Underestimating non-calcemic toxicity: Vitamin D toxicity may cause cardiovascular calcification and atherosclerosis even without severe hypercalcemia 2, 6

The management of vitamin D toxicity requires prompt recognition, immediate discontinuation of vitamin D sources, and aggressive treatment of hypercalcemia to prevent long-term complications including renal damage and cardiovascular calcification.