Treatment Plan for Vitamin D Deficiency
For vitamin D deficiency (<20 ng/mL), start with oral ergocalciferol (vitamin D2) 50,000 IU once weekly for 8-12 weeks, followed by maintenance therapy of 800-2000 IU daily of vitamin D3. 1, 2
Initial Treatment Based on Deficiency Severity
- For vitamin D deficiency (<20 ng/mL), begin with a loading dose regimen of 50,000 IU ergocalciferol (vitamin D2) once weekly for 8 weeks 2
- For severe vitamin D deficiency (<10 ng/mL), use 50,000 IU weekly for 12 weeks followed by monthly maintenance 1
- Each 1,000 IU of vitamin D supplementation typically increases serum 25(OH)D levels by approximately 10 ng/mL, though individual responses vary significantly 2
- For convenience, a monthly dose of 50,000 IU can achieve the equivalent of approximately 1,600 IU daily 1
Maintenance Phase
- After completing the loading dose regimen, transition to a maintenance dose of 800-2000 IU daily 2
- Vitamin D3 (cholecalciferol) is preferred over vitamin D2 (ergocalciferol) for maintenance therapy, especially when using intermittent dosing regimens 2, 3
- For patients who prefer less frequent dosing, 50,000 IU monthly can be an effective maintenance option 2
- Ensure adequate calcium intake alongside vitamin D supplementation, with a recommended daily intake of 1000-1500 mg 1, 4
Special Populations
- For obese patients or those with malabsorption syndromes, higher maintenance doses (2000-4000 IU daily) may be required 2, 5
- For elderly patients (≥65 years), institutionalized individuals, and those with dark skin or limited sun exposure, supplementation with 800 IU/day is recommended 2
- For patients with chronic kidney disease (CKD) and GFR of 20-60 mL/min/1.73m², vitamin D supplementation is particularly important 1, 6
- For patients with liver failure or severe intestinal malabsorption syndromes, calcifediol may be considered instead of cholecalciferol 3
Monitoring Response to Treatment
- Measure 25(OH)D levels after 3-6 months of supplementation to allow serum levels to reach plateau 1, 2
- Target 25(OH)D level should be at least 30 ng/mL (75 nmol/L) for optimal health benefits 1, 2
- The upper safety limit for 25(OH)D is considered to be 100 ng/mL (250 nmol/L) 2
Important Considerations
- Vitamin D supplementation benefits are primarily seen in those with documented deficiency, not in the general population with normal levels 1
- Daily doses up to 4000 IU are generally considered safe for adults 1
- Vitamin D toxicity is rare but can occur with prolonged high doses (typically >10,000 IU daily) 1, 7
- Avoid single very large doses (300,000-500,000 IU) as these may be inefficient or potentially harmful 1, 8
- Take vitamin D supplements with food as directed on medication labels 9
Alternative Dosing Calculations
- For a more precise approach, the cholecalciferol loading dose required to reach the target serum 25(OH)D level of 75 nmol/L can be calculated as: dose (IU) = 40 × (75 - serum 25(OH)D) × body weight 10
- For patients with obesity, liver disease or malabsorption syndromes, higher daily doses (7000 IU/day) or intermittent doses (30,000 IU/week) may be considered as maintenance therapy 5