What is the treatment for a vitamin D deficiency with a level of 13.2 ng/mL?

Treatment for Vitamin D Level of 13.2 ng/mL

For a vitamin D level of 13.2 ng/mL, initiate ergocalciferol (vitamin D2) or cholecalciferol (vitamin D3) 50,000 IU once weekly for 8-12 weeks, followed by maintenance therapy with 800-2,000 IU daily. 1

Understanding the Severity

• A level of 13.2 ng/mL represents moderate to severe vitamin D deficiency, falling well below the 20 ng/mL threshold that defines deficiency 1, 2
• This level is associated with increased risk of secondary hyperparathyroidism, accelerated bone loss, increased fall risk, and fracture risk 1, 2
• Levels below 12 ng/mL dramatically increase risk for osteomalacia, though your level is just above this critical threshold 1, 3

Loading Phase Treatment Protocol

• Administer 50,000 IU of vitamin D2 (ergocalciferol) or D3 (cholecalciferol) once weekly for 8-12 weeks as the standard loading regimen 1, 2
• For this level of deficiency (13.2 ng/mL), the full 12-week course is recommended rather than the shorter 8-week option 1
• Cholecalciferol (D3) is strongly preferred over ergocalciferol (D2) because it maintains serum levels longer and has superior bioavailability, particularly when using intermittent dosing schedules 1

Essential Co-Interventions

• Ensure adequate calcium intake of 1,000-1,500 mg daily from diet plus supplements if needed, as adequate dietary calcium is necessary for response to vitamin D therapy 1, 4
• Calcium supplements should be taken in divided doses of no more than 600 mg at once for optimal absorption 1
• Take the weekly vitamin D dose with the largest, fattiest meal of the day to maximize absorption, as vitamin D is fat-soluble 1

Maintenance Phase

• After completing the 12-week loading phase, transition to maintenance therapy with 800-2,000 IU daily 1
• The higher end of this range (2,000 IU daily) is recommended for optimal health benefits and to prevent recurrence 1
• An alternative maintenance regimen is 50,000 IU monthly, which is equivalent to approximately 1,600 IU daily 1

Monitoring Protocol

• Recheck 25-hydroxyvitamin D [25(OH)D] levels 3 months after initiating treatment to allow sufficient time for levels to plateau and accurately reflect response to supplementation 1
• The target level is at least 30 ng/mL for optimal health benefits, particularly for anti-fracture efficacy 1, 2
• Anti-fall efficacy begins at achieved levels of at least 24 ng/mL, while anti-fracture efficacy requires at least 30 ng/mL 1
• If using the weekly dosing regimen, measure levels just prior to the next scheduled dose 1
• Once stable and in target range, recheck levels at least annually 1

Expected Response

• The standard 50,000 IU weekly regimen for 12 weeks typically raises 25(OH)D levels by approximately 16-28 ng/mL 1
• Starting from 13.2 ng/mL, you should achieve a final level of approximately 29-41 ng/mL if responding normally 1
• Using the rule of thumb, an intake of 1,000 IU vitamin D daily increases serum 25(OH)D by approximately 10 ng/mL, though individual responses vary 1

Critical Pitfalls to Avoid

• Never use active vitamin D analogs (calcitriol, alfacalcidol, doxercalciferol, paricalcitol) to treat nutritional vitamin D deficiency, as they bypass normal regulatory mechanisms, do not correct 25(OH)D levels, and carry higher risk of hypercalcemia 1, 5
• Avoid single very large doses (>300,000 IU) as they may be inefficient or potentially harmful 1
• Do not measure vitamin D levels too early (before 3 months), as this will not reflect true steady-state levels and may lead to inappropriate dose adjustments 1
• Verify patient adherence with the prescribed regimen before increasing doses for inadequate response 1

Safety Considerations

• Daily doses up to 4,000 IU are generally safe for adults, with some evidence supporting up to 10,000 IU daily for several months without adverse effects 1
• The upper safety limit for 25(OH)D is 100 ng/mL 1
• Toxicity is rare but can occur with prolonged high doses (typically >10,000 IU daily) and may cause hypercalcemia, hypercalciuria, and renal issues 1
• Monitor for symptoms of hypercalcemia as vitamin D stores replete, particularly if calcium supplementation is also being used 1

Special Population Considerations

• If you have chronic kidney disease (CKD) stages 3-4, use the same standard nutritional vitamin D replacement with ergocalciferol or cholecalciferol—never active vitamin D analogs for nutritional deficiency 1, 5
• If you have malabsorption syndromes (post-bariatric surgery, inflammatory bowel disease, celiac disease, pancreatic insufficiency), consider intramuscular vitamin D 50,000 IU as the preferred route, as IM administration results in higher 25(OH)D levels and lower rates of persistent deficiency compared to oral supplementation 1
• If you are elderly (≥65 years), ensure maintenance doses are at least 800 IU daily, though 700-1,000 IU daily is more effective for fall and fracture prevention 1, 5
• If you have obesity, you may require higher doses due to vitamin D sequestration in adipose tissue 1