Vitamin D Dosing for Deficiency Treatment
For vitamin D deficiency, the recommended treatment is ergocalciferol (vitamin D2) or cholecalciferol (vitamin D3) 50,000 IU weekly for 8 weeks, followed by maintenance therapy of 1,000-2,000 IU daily or 50,000 IU monthly. 1
Initial Treatment Based on Deficiency Severity
Severe deficiency (<5 ng/mL):
- 50,000 IU of vitamin D (preferably ergocalciferol/D2) weekly for 8-12 weeks 1
Mild deficiency (5-15 ng/mL):
- 50,000 IU of vitamin D weekly for 8 weeks 1
Insufficiency (16-30 ng/mL):
- Ergocalciferol (vitamin D2) 50,000 IU weekly for 8 weeks 1
Maintenance Therapy
After the initial repletion phase:
Special Populations Requiring Modified Approaches
- Elderly (≥65 years): 800 IU/day 1
- Dark-skinned or veiled individuals: 800 IU/day 1
- Institutionalized individuals: 800 IU/day 1
- Obese patients: Consider higher doses - 7,000 IU daily or 30,000 IU weekly as maintenance 3
- Patients with malabsorption: May require higher doses - consider 30,000 IU twice weekly 3
- Chronic kidney disease patients: Specialized approaches for those with GFR 20-60 mL/min/1.73m² 1
Monitoring and Follow-up
- Check 25(OH)D levels after 3 months of supplementation 1
- Adjust dosing based on follow-up levels
- Target serum 25(OH)D levels above 30 ng/mL (75 nmol/L) 1
- Continue monitoring periodically, especially in high-risk individuals 1
Safety Considerations
- Safe upper limit for most adults is 4,000 IU daily 1
- Higher-risk patients may safely take up to 10,000 IU daily under medical supervision 1
- Ultra-high single loading doses (>300,000 IU) are not recommended 1
- Vitamin D toxicity typically occurs at levels above 150 ng/mL 1
- Monitor for signs of toxicity such as hypercalcemia, hypercalciuria, and nephrocalcinosis 1
Clinical Pearls
- Both vitamin D2 and D3 are effective, though D3 may be more bioavailable long-term 1
- The FDA-labeled dose for ergocalciferol (400 IU daily) 4 is significantly lower than treatment doses recommended in clinical guidelines and is inadequate for treating deficiency
- Recent evidence suggests that about 5,000 IU/day is typically needed to correct deficiency in many adults 5
- Long-term supplementation with doses ranging from 5,000 to 50,000 IU/day appears to be safe in clinical practice 6
Common Pitfalls to Avoid
- Underdosing is common - the recommended daily allowance is often inadequate for correcting deficiency 5
- Failing to account for factors that affect vitamin D requirements (obesity, age, albumin levels, baseline vitamin D status) 5
- Not continuing long enough with maintenance therapy after initial repletion
- Not monitoring levels after treatment to ensure adequacy