What is the recommended vitamin D replacement therapy for patients with a confirmed vitamin D deficiency?

Vitamin D Replacement Therapy for Confirmed Deficiency

For patients with confirmed vitamin D deficiency, the recommended treatment is 50,000 IU of ergocalciferol (vitamin D2) weekly for 8 weeks, followed by maintenance therapy with cholecalciferol (vitamin D3) at 800-1,000 IU daily. 1

Treatment Strategy Based on Deficiency Severity

Treatment should be tailored according to the patient's vitamin D levels:

• Mild deficiency (15-20 ng/mL): 800-1,000 IU/day 2
• Moderate deficiency (5-15 ng/mL): 50,000 IU weekly for 4-8 weeks, then maintenance 2
• Severe deficiency (<5 ng/mL): Individualized treatment under close monitoring 2

Special Populations Requiring Modified Dosing

Different populations require adjusted dosing strategies:

• Elderly (≥65 years): Minimum 800 IU daily 2
• Patients with obesity: 2-3 times higher doses (up to 7,000 IU daily) 2
• Malabsorption syndromes: Higher doses or weekly regimens; in severe cases, may require 50,000 IU 1-3 times weekly to daily 3, 2
• Bariatric surgery patients: 3,000 IU daily, titrated to reach 25(OH)D levels ≥30 ng/mL, may require up to 6,000 IU daily 3
• Chronic kidney disease: Specialized approaches including ergocalciferol supplementation for CKD with GFR 20-60 mL/min/1.73m² 2

Maintenance Therapy

After correcting deficiency, maintenance therapy is essential:

• Standard maintenance: 800-1,000 IU vitamin D3 daily 1
• Elderly adults: 800 IU daily 2
• Adults (19-70 years): 600 IU daily 2
• Adults (>70 years): 800 IU daily 2

Monitoring and Safety Considerations

• Measure serum 25(OH)D levels 3-4 months after initiating therapy to assess response 2
• The safe upper limit for vitamin D supplementation is generally 4,000 IU daily for adults 2, 4
• Single large doses of 300,000-500,000 IU should be avoided 2, 4
• Monitor serum calcium and phosphorus during supplementation 2
• Important caveat: Adequate calcium intake (1,000-1,500 mg daily) is necessary alongside vitamin D supplementation for optimal bone health and response to therapy 2, 5

Clinical Considerations

• Recent research suggests that a daily dose of 2,000 IU (50 μg) of vitamin D3 may be sufficient to raise and maintain serum 25(OH)D concentrations above 50 nmol/L (20 ng/mL) in >99% of adults and above 75 nmol/L (30 ng/mL) in >90% of adults 6
• For patients requiring rapid repletion, a cumulative dose of at least 600,000 IU administered over several weeks appears necessary to replenish vitamin D stores 4
• Factors affecting response to supplementation include starting serum concentration, BMI, age, and serum albumin concentration 7

Common Pitfalls to Avoid

• Underdosing: The recommended daily allowance is often inadequate for correcting deficiency; about 5,000 IU vitamin D3/day is typically needed 7
• Inadequate calcium: Vitamin D therapy is less effective without adequate calcium intake 5
• Insufficient monitoring: Failure to reassess vitamin D levels after initiating therapy
• Ignoring comorbidities: Conditions affecting absorption or metabolism require dose adjustments
• Overlooking drug interactions: Some medications (e.g., anticonvulsants, glucocorticoids) may increase vitamin D requirements