What is the treatment for a patient with vitamin D (25-hydroxyvitamin D) deficiency?

Treatment of Vitamin D Deficiency (Level 25 ng/mL)

For a patient with vitamin D level of 25 ng/mL (deficiency defined as <30 ng/mL), initiate ergocalciferol 50,000 IU once weekly for 8 weeks, followed by maintenance therapy with cholecalciferol 1,000-2,000 IU daily to achieve and maintain levels above 30 ng/mL. 1, 2, 3

Initial Loading Phase

• Administer ergocalciferol (vitamin D2) 50,000 IU once weekly for 8 weeks as the standard loading regimen to rapidly correct deficiency 1, 2, 3
• This regimen effectively raises vitamin D levels in most patients and has been validated across multiple guidelines 1, 3
• The goal is to achieve a target 25(OH)D level of at least 30-40 ng/mL for optimal health benefits 4, 5, 1

Maintenance Therapy

• After completing the 8-week loading dose, transition to cholecalciferol (vitamin D3) 1,000-2,000 IU daily for long-term maintenance 1, 2, 3
• Vitamin D3 is preferred over vitamin D2 for maintenance therapy because it provides better sustained serum levels, especially with longer dosing intervals 5, 1, 2
• As a general rule, each 1,000 IU of daily vitamin D raises serum levels by approximately 10 ng/mL 2

Calcium Co-Administration

• Ensure adequate calcium intake of 1,000-1,500 mg daily through diet or supplements 5, 1, 2
• Take calcium supplements in divided doses of no more than 600 mg at a time for optimal absorption 5, 1, 2
• Adequate dietary calcium is necessary for clinical response to vitamin D therapy 6

Monitoring Protocol

• Recheck 25(OH)D levels after 3 months of therapy to ensure adequate response 4, 5, 1, 2
• Use an assay that measures both 25(OH)D2 and 25(OH)D3 for accurate assessment 4, 5
• If levels remain below 30 ng/mL despite good adherence, increase maintenance dose or consider additional loading doses 4

Important Caveats

• The upper safety limit for 25(OH)D is 100 ng/mL—avoid excessive supplementation 4, 5
• Mineral oil interferes with absorption of fat-soluble vitamins including vitamin D 6
• Thiazide diuretics can cause hypercalcemia when combined with vitamin D supplementation 6
• Overweight patients (BMI >25 kg/m²) may require higher doses as they achieve vitamin D sufficiency less effectively than those with normal BMI 7
• For patients with malabsorption syndromes (inflammatory bowel disease, gastric bypass), higher doses may be required 2, 8

Dosing Adjustments for Special Populations

• Patients with chronic kidney disease: Vitamin D supplementation should be guided by their specific stage of kidney disease, as they may require active vitamin D analogs rather than nutritional vitamin D 4, 2
• Patients with chronic liver disease: Supplement those with vitamin D levels below 20 ng/mL until reaching above 30 ng/mL; higher doses may be necessary in non-alcoholic fatty liver disease 4