What is the treatment for vitamin D (Vit 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, with cholecalciferol (D3) strongly preferred over ergocalciferol (D2) due to superior bioavailability and longer-lasting serum levels. 1, 2

Diagnostic Thresholds

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

Loading Phase Treatment Protocol

• Administer 50,000 IU of vitamin D2 (ergocalciferol) or D3 (cholecalciferol) once weekly for 8-12 weeks to rapidly correct deficiency 1, 2, 3
• Cholecalciferol (D3) is strongly preferred over ergocalciferol (D2) because it maintains serum levels longer and has superior bioavailability, particularly important with intermittent dosing schedules 1, 2, 4
• For severe deficiency (<10 ng/mL), especially with symptoms or high fracture risk, use 50,000 IU weekly for the full 12 weeks 1

Maintenance Phase After Loading

• Transition to 1,500-2,000 IU daily after completing the 8-12 week loading phase 1, 2
• Alternative maintenance regimen: 50,000 IU monthly (equivalent to approximately 1,600 IU daily), which may improve adherence 1, 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

• Target 25(OH)D level: ≥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 3-6 months after initiating treatment to confirm adequate response 1, 2
• If using intermittent dosing (weekly or monthly), measure levels just prior to the next scheduled dose 1
• Upper safety limit is 100 ng/mL 1, 2

Essential Co-Interventions

• Ensure adequate calcium intake of 1,000-1,500 mg daily from diet plus supplements, as calcium is necessary for clinical response to vitamin D therapy 1, 2, 5
• Calcium supplements should be taken in divided doses of no more than 600 mg at once for optimal absorption 1, 2
• Weight-bearing exercise at least 30 minutes, 3 days per week supports bone health 1, 2

Special Populations

Chronic Kidney Disease

• For CKD patients with GFR 20-60 mL/min/1.73m², use standard nutritional vitamin D replacement with 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 when available 1
• When IM is unavailable or contraindicated, 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 do not correct 25(OH)D levels and bypass the body's regulatory mechanisms 1, 2
• Avoid single very large doses (>300,000 IU) as they may be inefficient or potentially harmful 1, 2, 6
• 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, 6
• 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
• The 50,000 IU weekly regimen is well-established as safe with no significant adverse events reported in clinical trials 1, 7

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, 8
• The total cumulative dose over 12 weeks (600,000 IU) produces a significant increase in 25(OH)D levels 1
• Individual response to vitamin D supplementation is variable due to genetic variations in vitamin D metabolism, making monitoring essential 1