What is the appropriate treatment regimen for a patient with vitamin D deficiency using vitamin D3 (cholecalciferol) 60,000 IU per week?

Vitamin D3 Supplementation at 60,000 IU Weekly

For patients with vitamin D deficiency, a regimen of 60,000 IU vitamin D3 weekly for 6-8 weeks is appropriate for initial treatment, followed by a maintenance dose of 1,000-2,000 IU daily or 30,000 IU weekly. 1, 2

Treatment Regimen for Vitamin D Deficiency

Initial Treatment Phase

• For severe deficiency (<5 ng/mL): 60,000 IU weekly for 8 weeks 1
• For mild-moderate deficiency (5-15 ng/mL): 60,000 IU weekly for 4-8 weeks 1, 2
• For insufficiency (16-30 ng/mL): Consider lower doses of 800-1,000 IU daily 1

Maintenance Phase

• After completing the loading dose regimen, transition to:
  • 1,000-2,000 IU daily for most adults
  • 30,000 IU weekly for those who prefer weekly dosing 2

Special Populations Requiring Higher Doses

• Obesity: Require 2-3 times higher doses (up to 7,000 IU daily) 1, 2
• Malabsorption syndromes: Minimum 2,000 IU daily or weekly regimens 1, 2
• Liver disease: Higher doses due to impaired hepatic 25-hydroxylation 1
• Elderly (≥65 years): Minimum 800 IU daily 1
• CKD patients: Specialized approaches based on GFR and PTH levels 1

Monitoring and Safety

Recommended Monitoring

• Measure serum 25(OH)D levels 3-4 months after initiating therapy 1
• Target range: 30-80 ng/mL (some experts recommend 30-100 ng/mL) 1
• Monitor serum calcium and phosphorus during supplementation, especially with high doses 1

Safety Considerations

• Vitamin D toxicity is rare but can occur with prolonged high doses 1
• Signs of toxicity typically occur with 25(OH)D levels >150 ng/mL 1
• Single large doses of 300,000-500,000 IU should be avoided 3
• The therapeutic window between effective and toxic doses is narrow 4

Important Caveats

• The FDA label notes that "dosage must be individualized under close medical supervision" for therapeutic doses 4
• For patients requiring vitamin D replacement, a cumulative dose of at least 600,000 IU administered over several weeks appears necessary to replenish vitamin D stores in severe deficiency 3, 5
• Weekly dosing of 60,000 IU has been safely tolerated in studies, even for prolonged periods, without causing hypercalcemia 6
• The response to vitamin D supplementation is affected by:
  • Starting serum 25(OH)D concentration
  • Body mass index (BMI)
  • Age
  • Serum albumin concentration 7

Practical Application

1. Assess baseline status: Ideally measure 25(OH)D level before starting treatment
2. Initial treatment: 60,000 IU weekly for 6-8 weeks
3. Re-assess: Check 25(OH)D levels after completion of loading dose
4. Maintenance: Transition to appropriate maintenance dose based on risk factors
5. Long-term monitoring: Annual 25(OH)D measurement for at-risk populations

The 60,000 IU weekly regimen provides a practical approach for correcting vitamin D deficiency, with good evidence for both efficacy and safety when used appropriately.