What is the recommended treatment for vitamin D (Vit D) deficiency?

Treatment of Vitamin D Deficiency

For adults with vitamin D deficiency (levels <20 ng/mL), the recommended treatment is 50,000 IU of vitamin D weekly for 4-8 weeks, followed by maintenance therapy, or alternatively, 8,000 IU daily for 4 weeks, then 4,000 IU daily for 2 months. 1

Treatment Based on Deficiency Severity

Treatment should be tailored according to the severity of vitamin D deficiency:

• Mild to moderate deficiency (5-15 ng/mL):

  • 50,000 IU weekly for 4-8 weeks, then maintenance, OR
  • 8,000 IU daily for 4 weeks, followed by 4,000 IU daily for 2 months 1

• Vitamin D insufficiency (16-30 ng/mL):

  • 800-1,000 IU daily, OR
  • 4,000 IU daily for 12 weeks, OR
  • 50,000 IU every other week for 12 weeks 1

• Severe deficiency (<5 ng/mL):

  • Requires individualized treatment under close monitoring 1

Form of Vitamin D

• Vitamin D3 (cholecalciferol) is preferred over vitamin D2 (ergocalciferol) for most patients, as it's more effective for maintaining serum 25(OH)D concentrations, especially with intermittent dosing regimens 1
• Caution: Vitamin D3 is a high-potency supplement; do not exceed recommended dosage 2

Special Populations Requiring Adjusted Dosing

Higher doses are recommended for:

• Patients with obesity: 2-3 times higher doses (up to 7,000 IU daily) 1
• Patients with malabsorption syndromes: Higher doses or weekly regimens 1
• Patients with liver disease: Higher doses due to impaired hepatic 25-hydroxylation 1
• Dark-skinned or veiled individuals: 800 IU/day 1
• Adults ≥65 years: 800 IU/day 1
• Institutionalized individuals: 800 IU/day 1
• Patients with chronic kidney disease: Specialized approaches, including ergocalciferol supplementation for CKD with GFR 20-60 mL/min/1.73m² 1

Monitoring and Maintenance

• Check vitamin D levels after 3 months of treatment to ensure target levels have been reached 1
• Monitor annually once stable 1
• Target serum levels:
  • Optimal range: 30-80 ng/mL
  • Target for bone health: 30-40 ng/mL 1
• Maintenance dosing once target levels achieved:
  • For most adults: 800-1,000 IU daily 1
  • For adults >70 years: 800 IU daily 1

Important Considerations

• Adequate calcium intake (1,000-1,500 mg daily) is necessary for response to vitamin D therapy 1, 3
• Monitor serum calcium and phosphorus at least every 3 months during recovery from vitamin D deficiency, especially if using higher doses or in patients with conditions affecting calcium metabolism 1
• Avoid single large doses of 300,000-500,000 IU as they may increase fracture risk 4
• Safety ceiling: The safe upper limit is generally considered to be 4,000 IU daily for adults 1
• Vitamin D toxicity is rare but typically occurs with doses >10,000 IU daily for extended periods, with serum levels >150 ng/mL indicating toxicity 1

Contraindications and Precautions

• Not recommended for children, pregnant or lactating women without medical supervision 2
• Use with caution in individuals with liver disease 2
• Patients taking thiazide diuretics may be at greater risk of toxicity 2

Mathematical Approach for Personalized Dosing

For more precise dosing, the following equation can be used to calculate the required loading dose to reach target levels 5:

Dose (IU) = 40 × (75 - current serum 25-OHD3) × body weight (kg)

This formula accounts for the observation that the change in 25-OHD3 is related to the dose per kilogram body weight 5.