Treatment of Vitamin D Deficiency
For vitamin D deficiency treatment, the recommended approach is to start with a large correcting dose of 50,000 IU vitamin D weekly for 8-12 weeks, followed by a maintenance dose of 800-2000 IU daily to maintain adequate levels. 1
Initial Assessment and Treatment Algorithm
Step 1: Diagnosis
- Vitamin D deficiency: 25(OH)D level <20 ng/mL (50 nmol/L)
- Vitamin D insufficiency: 25(OH)D level 20-30 ng/mL (50-75 nmol/L)
Step 2: Initial Treatment (Correcting Phase)
- Standard regimen: Vitamin D2 (ergocalciferol) 50,000 IU once weekly for 8-12 weeks 1
- 8 weeks for mild-moderate deficiency (15-20 ng/mL)
- 12 weeks for severe deficiency (<15 ng/mL)
Step 3: Maintenance Phase
- After completion of correcting phase, transition to:
Special Considerations
Choice of Vitamin D Form
- Vitamin D3 (cholecalciferol) is preferred over D2 (ergocalciferol) for maintenance therapy when both are available 1
- D3 maintains serum 25(OH)D concentration for longer periods when using intermittent dosing 1
- For daily dosing, D2 and D3 have similar effects on 25(OH)D levels 1
High-Risk Populations Requiring Higher Doses
For patients with increased risk of vitamin D deficiency:
- Obesity: Consider 7000 IU/day or 30,000 IU/week 3
- Malabsorption syndromes: Consider 30,000 IU twice weekly 3
- Elderly patients: May require higher doses due to decreased absorption 4
- Patients on multiple medications: May need higher doses due to drug interactions 3
Monitoring
- Measure 25(OH)D levels after 3-6 months of supplementation 1
- Goal: Achieve 25(OH)D level >30 ng/mL (75 nmol/L) 1
- Adjust dose based on follow-up levels
Safety Considerations
Potential Pitfalls
- Drug interactions: Mineral oil interferes with vitamin D absorption; thiazide diuretics may cause hypercalcemia in patients taking vitamin D 4
- Dosing intervals: Longer dosing intervals than weekly may be inefficient or potentially harmful 1
- Toxicity risk: Rare with standard dosing but possible with prolonged high doses (>10,000 IU daily) 1
- Treatment resistance: Consider sublingual administration for patients with poor oral absorption 5
Calcium Supplementation
- Consider calcium needs based on patient's diet
- Calcium supplementation may be necessary alongside vitamin D, especially in older adults
Evidence Quality Assessment
The recommendations are primarily based on clinical practice guidelines from expert panels. The most recent evidence 1, 3 supports higher maintenance doses (up to 7000 IU/day) for high-risk populations, while older guidelines 1 established the standard corrective regimen of 50,000 IU weekly for 8-12 weeks followed by lower maintenance doses. There is strong evidence that vitamin D supplementation of at least 700-800 IU daily reduces fracture and fall rates in adults 2.