What is the treatment for vitamin D deficiency?

Treatment of Vitamin D Deficiency

For vitamin D deficiency (25(OH)D <20 ng/mL), treat with ergocalciferol or cholecalciferol 50,000 IU once weekly for 8-12 weeks, followed by maintenance therapy with 1,500-2,000 IU daily or 50,000 IU monthly to achieve and maintain levels ≥30 ng/mL. 1

Understanding Deficiency Levels

• Deficiency is defined as 25(OH)D <20 ng/mL and requires treatment 1, 2
• Severe deficiency (<10-12 ng/mL) significantly increases risk for osteomalacia and rickets, demanding urgent treatment 1, 2
• Insufficiency (20-30 ng/mL) warrants treatment if the patient has osteoporosis, fracture risk, falls, or is elderly 2

Loading Phase Protocol

Cholecalciferol (vitamin D3) is strongly preferred over ergocalciferol (vitamin D2) because it maintains serum levels longer and has superior bioavailability, particularly with intermittent dosing schedules 1, 3, 2

• Administer 50,000 IU once weekly for 8-12 weeks 1, 2, 4
• This cumulative dose of 400,000-600,000 IU over 8-12 weeks is necessary to replenish vitamin D stores 1, 5
• The standard loading regimen applies to both vitamin D2 and D3, though D3 is preferred 1, 3

Maintenance Phase After Loading

After completing the loading phase, transition to maintenance therapy with 1,500-2,000 IU daily 1, 2

• An alternative maintenance regimen is 50,000 IU monthly, equivalent to approximately 1,600 IU daily, which may improve adherence 1, 3, 2
• For elderly patients (≥65 years), a minimum of 800 IU daily is recommended, though higher doses of 700-1,000 IU daily reduce fall and fracture risk more effectively 1, 2

Target Levels and Monitoring

The minimum target level is 25(OH)D ≥30 ng/mL for optimal bone health and anti-fracture efficacy 1, 2

• Anti-fall efficacy begins at ≥24 ng/mL 1, 2
• Recheck 25(OH)D levels 3 months after starting maintenance therapy to confirm adequate response 1, 3, 2
• If using intermittent dosing (weekly or monthly), measure levels just prior to the next scheduled dose 1
• The upper safety limit is 100 ng/mL; levels above this increase toxicity risk 1, 2

Essential Co-Interventions

Adequate calcium intake of 1,000-1,500 mg daily from diet plus supplements is essential, as calcium is necessary for clinical response to vitamin D therapy 1, 3, 2

• Calcium supplements should be taken in divided doses of no more than 600 mg at once for optimal absorption 1, 3, 2
• Weight-bearing exercise at least 30 minutes, 3 days per week supports bone health 1, 2

Special Populations Requiring Modified Approaches

Chronic Kidney Disease

• For CKD patients with GFR 20-60 mL/min/1.73m², use standard nutritional vitamin D (ergocalciferol or cholecalciferol), not active vitamin D analogs 1, 2
• CKD patients are at particularly high risk due to reduced sun exposure, dietary restrictions, and increased urinary losses 1

Malabsorption Syndromes

For patients with malabsorption (post-bariatric surgery, inflammatory bowel disease, celiac disease, short-bowel syndrome), intramuscular vitamin D3 50,000 IU is the preferred route 1

• IM administration results in significantly higher 25(OH)D levels and lower rates of persistent deficiency compared to oral supplementation 1
• When IM is unavailable or contraindicated (anticoagulation, infection risk), use substantially higher oral doses: 4,000-5,000 IU daily for 2 months 1
• Post-bariatric surgery patients specifically need at least 2,000 IU daily maintenance to prevent recurrent deficiency 1

Elderly and High-Risk Groups

• Dark-skinned or veiled individuals with limited sun exposure should receive 800 IU daily without baseline testing 1, 2
• Institutionalized individuals should receive 800 IU daily 1, 2

Critical Pitfalls to Avoid

Never use active vitamin D analogs (calcitriol, alfacalcidol, doxercalciferol, paricalcitol) to treat nutritional vitamin D deficiency, as they bypass the body's regulatory mechanisms and do not correct 25(OH)D levels 1, 3, 2

• Avoid single very large doses (>300,000 IU) as they may be inefficient or potentially harmful 1, 2, 5
• Do not supplement patients with normal vitamin D levels, as benefits are only seen in those with documented deficiency 1, 2
• Correct vitamin D deficiency before initiating bisphosphonates to prevent hypocalcemia 2

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, 2, 5

• Toxicity is rare, typically occurring only with prolonged high doses (>10,000 IU daily) and manifests as hypercalcemia, hyperphosphatemia, suppressed parathyroid hormone, and hypercalciuria 1, 2
• Monitor serum calcium, especially in CKD patients 2
• Thiazide diuretics may cause hypercalcemia when given to patients concurrently treated with ergocalciferol 6

Expected Clinical Response

Using the general rule, each 1,000 IU of daily vitamin D intake increases serum 25(OH)D by approximately 10 ng/mL, though individual responses vary based on baseline levels, body weight, and genetic factors 1, 3

• Individual response to vitamin D supplementation is variable due to genetic variations in vitamin D metabolism 1
• Body composition affects requirements: high body fat sequesters vitamin D, while high muscle mass increases retention 1
• Skin pigmentation affects synthesis: darker skin requires more sun exposure but has genetic polymorphisms that counteract decreased synthesis 1