What is the recommended once a week dosing regimen for vitamin D (Vit D) deficiency?

Weekly Vitamin D Dosing Regimen for Deficiency

For vitamin D deficiency, the recommended once-weekly dosing regimen is 50,000 IU of vitamin D2 (ergocalciferol) once weekly for 8 weeks as the initial treatment, followed by a maintenance dose of 800-2,000 IU daily or its weekly equivalent 1, 2.

Initial Treatment Phase

• For patients with vitamin D deficiency (<20 ng/mL), start with 50,000 IU of vitamin D2 once weekly for 8 weeks as the loading dose 1, 3
• For severe deficiency (<10-12 ng/mL), the same regimen of 50,000 IU weekly may be extended to 8-12 weeks 1, 2
• This loading dose approach is designed to rapidly correct deficiency and improve clinical outcomes related to bone health and muscle function 4

Maintenance Phase

• After completing the loading dose regimen, transition to a maintenance dose of 800-2,000 IU daily or its weekly equivalent 1, 4
• For weekly maintenance dosing, 50,000 IU monthly or 100,000 IU every 3 months are effective options 1, 3
• Vitamin D3 (cholecalciferol) is preferred over vitamin D2 (ergocalciferol) for maintenance therapy, especially when using intermittent dosing regimens 1, 3

Special Populations Requiring Higher Doses

• For patients with obesity, liver disease, or malabsorption syndromes, higher maintenance doses may be required 5:

  • 7,000 IU daily or 30,000 IU weekly as prophylactic or maintenance doses 5
  • For treatment without 25(OH)D assessment, 30,000 IU twice weekly or 50,000 IU weekly for 6-8 weeks 5

• For patients not responding to standard doses, consider:

  • Higher maintenance doses (2,000-4,000 IU daily) for those with obesity or malabsorption 1, 2
  • More frequent monitoring of 25(OH)D levels 3

Monitoring Response

• Measure 25(OH)D levels after at least 3 months of supplementation to allow serum levels to reach plateau 1, 3
• Target 25(OH)D level should be at least 30 ng/mL for optimal health benefits 1, 2
• If levels remain insufficient after initial treatment, increase the maintenance dose and recheck in 3 months 2, 6

Important Considerations

• Daily dosing is physiologically more natural, but weekly dosing with vitamin D3 has similar effects on 25(OH)D concentrations 3, 1
• Avoid single very large doses (>300,000 IU) as they may be inefficient or potentially harmful 2, 7
• Ensure adequate calcium intake alongside vitamin D supplementation (1,000-1,500 mg daily) 1, 2
• The upper safety limit for 25(OH)D is considered to be 100 ng/mL, with daily doses up to 4,000 IU generally considered safe for adults 3, 2
• Research suggests that 2,000 IU daily may not be sufficient to maintain levels above 30 ng/mL in some patients, highlighting the importance of monitoring 6