Treatment of Vitamin D Deficiency
For vitamin D deficiency, treatment should consist of 50,000 IU of vitamin D weekly for 4-8 weeks for those with levels 5-15 ng/mL, followed by maintenance therapy of 800-1,000 IU daily. 1
Diagnosis and Classification
Vitamin D status is determined by measuring serum 25-hydroxyvitamin D [25(OH)D] levels:
- Deficiency: <20 ng/mL (<50 nmol/L)
- Insufficiency: 20-30 ng/mL (50-75 nmol/L)
- Optimal levels: 30-80 ng/mL (75-200 nmol/L)
Treatment Protocol Based on Severity
Mild to Moderate Deficiency (5-15 ng/mL)
- First-line treatment: 50,000 IU weekly for 4-8 weeks 1
- Alternative approach: 8,000 IU daily for 4 weeks, then 4,000 IU daily for 2 months 1
Vitamin D Insufficiency (16-30 ng/mL)
- Standard approach: 800-1,000 IU daily 1
- Alternative regimens:
- 4,000 IU daily for 12 weeks
- 50,000 IU every other week for 12 weeks 1
Severe Deficiency (<5 ng/mL)
- Requires individualized treatment under close monitoring 1
- A cumulative dose of at least 600,000 IU administered over several weeks is typically necessary to replenish vitamin D stores 2
- Caution: Avoid single large doses of 300,000-500,000 IU 2
Special Populations Requiring Adjusted Dosing
- Dark-skinned or veiled individuals: 800 IU/day 1
- Adults ≥65 years: 800 IU/day 1
- Institutionalized individuals: 800 IU/day 1
- Patients with obesity: 2-3 times higher doses (up to 7,000 IU daily) 1
- Patients with malabsorption syndromes: Higher doses or weekly regimens 1
- Patients with liver disease: Higher doses due to impaired hepatic 25-hydroxylation 1
- Patients with chronic kidney disease: Specialized approaches, including ergocalciferol supplementation for CKD with GFR 20-60 mL/min/1.73m² 1
Maintenance and Monitoring
- Check vitamin D levels after 3 months of treatment to ensure target levels have been reached 1
- Monitor annually once stable 1
- Maintenance dosing after correction of deficiency: 800-1,000 IU daily 1, 3
- Target serum level: 30-50 ng/mL for optimal bone health 1
- Monitor serum calcium and phosphorus at least every 3 months during recovery from vitamin D intoxication or when using higher doses 1
Form of Vitamin D
- Preferred form: Vitamin D3 (cholecalciferol) is more effective than vitamin D2 (ergocalciferol), especially for maintaining serum levels with intermittent dosing regimens 1
- For initial treatment of deficiency, either form can be used, but D3 is generally preferred for long-term maintenance 1
Important Clinical Considerations
- Calcium intake: Ensure adequate calcium intake (1000-1500 mg daily) alongside vitamin D supplementation for optimal bone health 1
- Safety profile: Vitamin D toxicity is rare and typically occurs with much higher doses (>10,000 IU daily for extended periods) 1
- Signs of toxicity: Serum 25(OH)D levels >150 ng/mL may indicate toxicity 1
- Common manifestations of deficiency: Symmetric low back pain, proximal muscle weakness, muscle aches, and throbbing bone pain 3
- Patient education: Provide guidance on proper dosing to prevent toxicity, and caution against unregulated supplements 1
Recent Research Insights
Recent evidence suggests that a daily dose of 2,000 IU (50 µg) of vitamin D3 may be sufficient to raise and maintain serum 25(OH)D concentrations above 50 nmol/L (20 ng/mL) in >99% of adults and above 75 nmol/L (30 ng/mL) in >90% of the general adult population 4. However, current guidelines still recommend the dosing protocol outlined above based on severity of deficiency.
Long-term supplementation with vitamin D3 in doses ranging from 5,000 to 50,000 IUs/day appears to be safe in monitored settings, though such high maintenance doses are not typically necessary for most patients 5.