Treatment of Vitamin D Deficiency
For vitamin D deficiency (levels <20 ng/mL), the recommended treatment is 50,000 IU of vitamin D weekly for 4-8 weeks, followed by maintenance therapy of 800-1,000 IU daily to achieve and maintain optimal serum levels of 30-80 ng/mL. 1
Diagnosis and Classification
- Vitamin D status classification:
- Deficiency: <20 ng/mL
- Insufficiency: 20-30 ng/mL
- Optimal range: 30-80 ng/mL
- Safe upper limit: 100 ng/mL 1
Treatment Algorithm
Initial Treatment Based on Severity
Mild deficiency (15-20 ng/mL):
- 800-1,000 IU/day 1
Moderate deficiency (5-15 ng/mL):
- 50,000 IU weekly for 4-8 weeks, then maintenance 1
Severe deficiency (<5 ng/mL):
- Individualized treatment under close monitoring 1
Maintenance Therapy
- After achieving target levels, continue with 800-1,000 IU daily 1, 2
- Ensure adequate calcium intake (1,000-1,500 mg daily) alongside vitamin D supplementation 1
Special Populations Requiring Higher Doses
Certain populations require specialized approaches with higher vitamin D doses:
- Obesity: 2-3 times higher doses (up to 7,000 IU daily) 1, 3
- Malabsorption syndromes: Higher doses or weekly regimens 1, 3
- Liver disease: Higher doses due to impaired hepatic 25-hydroxylation 1, 3
- Elderly (≥65 years): 800 IU/day minimum 1
- Dark-skinned or veiled individuals: 800 IU/day minimum 1
- Institutionalized individuals: 800 IU/day minimum 1
- Chronic kidney disease: Specialized approaches based on GFR 1
Monitoring
- Check vitamin D levels 3 months after initiating treatment to ensure target levels have been reached 1
- Monitor annually once stable 1
- For patients on higher doses, monitor serum calcium and phosphorus 1
- The Ca × P product should not exceed 70 mg²/dL² 4
Important Precautions
- Avoid excessive supplementation: Overdosage of vitamin D can lead to hypercalcemia, hypercalciuria, and hyperphosphatemia 4
- Avoid single large doses: Single doses of 300,000-500,000 IU should be avoided 5
- Drug interactions: Withhold pharmacologic doses of other vitamin D preparations during treatment to avoid additive effects 4
- Avoid concomitant use: Magnesium-containing preparations (e.g., antacids) and calcitriol should not be used together in patients on chronic renal dialysis 4
Treatment Response
Research shows that approximately 5,000 IU/day is typically needed to correct deficiency in many adult patients 6. Long-term supplementation with doses ranging from 5,000 to 50,000 IU/day has been shown to be safe in hospitalized patients without causing hypercalcemia 7.
Pitfalls to Avoid
- Inadequate dosing: The recommended daily allowance is often insufficient to correct deficiency 6
- Failure to monitor: Not checking vitamin D levels after initiating treatment can lead to persistent deficiency or toxicity
- Ignoring calcium intake: Adequate calcium is necessary alongside vitamin D for optimal bone health 1
- Switching between vitamin D forms: When switching from ergocalciferol (D2) to calcitriol, it may take several months for blood levels to normalize 4