What is the treatment for vitamin D toxicity?

Treatment of Vitamin D Toxicity

The primary treatment for vitamin D toxicity includes discontinuation of vitamin D supplementation, low calcium and phosphorus diet, intravenous hydration with saline, loop diuretics, glucocorticoids, calcitonin, and bisphosphonates. 1

Diagnosis and Clinical Features

Vitamin D toxicity is characterized by:

• Serum 25(OH)D levels above 150 ng/ml
• Hypercalcemia
• Normal or high serum phosphorus levels
• Normal or low levels of alkaline phosphatase
• Low serum parathyroid hormone
• High urine calcium/creatinine ratio 1, 2

Clinical manifestations include:

• Generalized symptoms (fatigue, weakness)
• Neurological symptoms (altered sensorium)
• Gastrointestinal symptoms (nausea, vomiting, constipation)
• Renal complications (acute kidney injury)
• Endocrinological disturbances 1, 3

Treatment Algorithm

Step 1: Emergency Assessment

• Immediate intervention is required when calcium concentration exceeds 14 mg/dL due to potential adverse effects on cardiac, central nervous system, renal, and gastrointestinal functions 1, 2

Step 2: Acute Management

1. Discontinue all vitamin D supplements - This is the first and most crucial step 1, 2
2. Aggressive hydration - Intravenous isotonic saline to promote calcium excretion 1, 2, 4
3. Loop diuretics (e.g., furosemide) - To enhance calcium excretion after adequate hydration 1, 2, 4
4. Low calcium and phosphorus diet - To reduce calcium absorption 1, 2

Step 3: Additional Pharmacological Interventions

For severe or persistent hypercalcemia:

• Glucocorticoids (e.g., prednisone) - Reduce intestinal calcium absorption and vitamin D activity 1, 2, 4
• Calcitonin - For rapid but short-term reduction of serum calcium 1, 2
• Bisphosphonates - For longer-term management of hypercalcemia 1, 2

Step 4: Monitoring and Follow-up

• Regular monitoring of serum calcium, phosphorus, creatinine, and 25(OH)D levels 1
• Continue treatment until normocalcemia is achieved
• Be aware that effects may persist for months since vitamin D is stored in fat tissues 2

Important Considerations and Pitfalls

1. Duration of treatment: Since vitamin D is fat-soluble and stored in adipose tissue, toxicity effects may last for months despite removal of the exogenous source 2

2. Common causes of toxicity to address:

   • Prescription of mega-doses of vitamin D (most common cause) 3
   • Manufacturing errors in supplements 5
   • Overzealous correction of vitamin D deficiency 3
   • Quality control issues with over-the-counter supplements 1

3. Prevention strategies:

   • Adhere to safe upper limits (generally 4,000 IU/day for adults) 1
   • Check serum 25(OH)D levels before initiating high-dose therapy 1
   • Avoid ultra-high single loading doses (>300,000 IU) 1
   • Question patients about all supplements they may be taking 2

4. Monitoring during recovery: Regular assessment of calcium levels is essential as hypercalcemia may persist or recur due to the slow release of vitamin D from fat stores 1, 2

5. Caution with concurrent medications: Some medications may worsen hypercalcemia or interact with treatments for vitamin D toxicity 1