Expected Vitamin D Level After 12 Weeks of 50,000 IU Twice Weekly
Starting from a severely deficient level of 8 ng/mL, taking 50,000 IU of vitamin D twice weekly for 12 weeks should raise your level to approximately 50-60 ng/mL, well above the target of 30 ng/mL. 1
Understanding Your Starting Point
Your baseline level of 8 ng/mL represents severe vitamin D deficiency, which significantly increases risk for bone complications and requires aggressive correction. 2 Severe deficiency is defined as levels below 10-12 ng/mL. 3, 2
Expected Response to 50,000 IU Twice Weekly
The twice-weekly regimen (100,000 IU total per week) is highly effective for rapid correction:
Research directly addressing this regimen shows that 50,000 IU twice weekly produces the most rapid and robust response among common dosing schedules, with levels reaching above 30 ng/mL after only 1 month and plateauing at approximately 60 ng/mL by 7 months. 1
Using the rule of thumb that 1,000 IU daily increases serum 25(OH)D by approximately 10 ng/mL, your weekly dose of 100,000 IU (equivalent to ~14,000 IU daily) would theoretically increase your level by approximately 140 ng/mL over time. 3 However, this is a rough estimate and actual response plateaus well before this theoretical maximum.
Research on single weekly dosing (50,000 IU once weekly, half your dose) showed an average increase of 21.6 ng/mL after 12 weeks. 4 Since you're taking twice this amount, you can expect a substantially greater increase.
Calculating Your Expected Level
Starting from 8 ng/mL:
- With 50,000 IU twice weekly, expect an increase of approximately 42-52 ng/mL over 12 weeks 1
- Your predicted level at 12 weeks: 50-60 ng/mL 1
- This falls well within the optimal target range of 30-80 ng/mL and below the safety limit of 100 ng/mL 3
Safety Considerations for This Regimen
This dosing schedule is safe and effective when given for up to 12 months, with serum vitamin D rarely exceeding 100 ng/mL and no significant changes in serum calcium or kidney function. 5
No episodes of significant hypercalcemia occurred in studies using 50,000-100,000 IU weekly. 5, 1
The upper safety limit for 25(OH)D is 100 ng/mL, which you are unlikely to exceed with this regimen. 3
Important Monitoring and Follow-Up
Recheck your vitamin D level after 3 months (12 weeks) to confirm adequate response and ensure you haven't exceeded safe levels. 3, 2
Ensure adequate calcium intake of 1,000-1,500 mg daily from diet plus supplements to support bone health during correction. 2
After achieving target levels (≥30 ng/mL), you'll need to transition to a maintenance dose of at least 2,000 IU daily, as research shows 2,000 IU daily is insufficient to maintain levels above 30 ng/mL in many patients. 6
Critical Pitfall to Avoid
Do not continue 50,000 IU twice weekly indefinitely. Once your level is corrected (typically by 3 months), transition to maintenance dosing of 2,000-4,000 IU daily or 50,000 IU monthly to prevent levels from becoming excessive. 3, 2