Recommended Weekly Vitamin D Dosing for Adults with Deficiency
For adults with vitamin D deficiency, the recommended regimen is 50,000 IU of vitamin D weekly for 8 weeks to correct the deficiency, followed by maintenance therapy of 800-2000 IU daily or 50,000 IU monthly. 1
Initial Treatment of Vitamin D Deficiency
Correction Phase
- Initial correction regimen: 50,000 IU weekly for 8 weeks 1, 2
- Alternative high-dose options for specific populations:
Target Levels
- Optimal target range: 30-40 ng/mL (75-100 nmol/L) 1
- Minimum target level: 20 ng/mL (50 nmol/L) 1
- Deficiency defined as: <20 ng/mL (50 nmol/L) 2
- Insufficiency defined as: 20-30 ng/mL (50-75 nmol/L) 2
Maintenance Therapy
After achieving target levels, transition to maintenance therapy:
- Standard maintenance: 800-2000 IU daily or 50,000 IU monthly 1, 2
- For high-risk populations (obesity, liver disease, malabsorption):
- 7000 IU daily or 30,000 IU weekly as maintenance 3
Special Considerations
Factors Affecting Dosing Requirements
Several factors affect vitamin D dosing requirements:
- Starting serum 25(OH)D concentration
- Body mass index (BMI)
- Age
- Serum albumin concentration 5
Population-Specific Recommendations
- Adults ≥65 years: 800 IU/day 1
- Dark-skinned or veiled individuals: 800 IU/day 1
- Institutionalized individuals: 800 IU/day 1
- Obese patients: Higher doses required (7000 IU/day or 30,000 IU/week) 3
Monitoring and Safety
Follow-up Testing
- Initial follow-up testing: After 3 months of supplementation 1
- For high-dose therapy: Check calcium and phosphorus monthly for first 3 months, then every 3 months 1
- PTH levels: Every 3 months for 6 months, then every 3 months thereafter 1
Safety Considerations
- Safety upper limit: 100 ng/mL (250 nmol/L) 1
- Toxicity typically occurs at levels above 150 ng/mL 1
- Avoid single large doses of 300,000-500,000 IU 4
- Discontinue therapy if serum corrected total calcium exceeds 10.2 mg/dL 1
Practical Implementation
- Long-term supplementation with vitamin D3 in doses ranging from 5000 to 50,000 IU/day has been shown to be safe in hospitalized patients 6
- Maintain normal calcium intake (1,000-1,200 mg daily) primarily from food sources 1
- Take calcium with meals to bind dietary oxalate in the gut 1
- Maintain high fluid intake to produce at least 2.5 liters of urine daily 1
Common Pitfalls
- Standard recommended daily allowances are often inadequate for correcting deficiency 5
- About 5000 IU vitamin D3/day is usually needed to correct deficiency 5
- Failure to account for factors like obesity, which increases dose requirements
- Inadequate monitoring of calcium levels during high-dose supplementation
- Insufficient duration of treatment during correction phase