What is the recommended vitamin D repletion regimen for a 65-year-old female with vitamin D deficiency?

Vitamin D Repletion for a 65-Year-Old Female with Vitamin D Deficiency

For a 65-year-old female with documented vitamin D deficiency (serum 25-OH vitamin D <20 ng/mL), initiate treatment with 50,000 IU of vitamin D2 or D3 weekly for 8 weeks, followed by maintenance therapy of 800-1,000 IU daily, combined with 1,200 mg of calcium daily. 1, 2

Initial Correction Phase

High-dose repletion is necessary to rapidly correct deficiency:

• Administer 50,000 IU of vitamin D weekly for 8 weeks as the standard correction regimen 1, 2
• Vitamin D3 (cholecalciferol) is preferred over vitamin D2 (ergocalciferol) when available, particularly for intermittent dosing regimens, as D3 maintains serum levels longer 1
• Alternative intermittent regimens may include 100,000 IU every 3 months, though weekly dosing is more commonly used for initial correction 1
• Avoid single annual high doses (≥500,000 IU) as these may paradoxically increase fall and fracture risk 3, 4

Maintenance Phase

After 8 weeks of correction, transition to long-term maintenance:

• 800-1,000 IU of vitamin D3 daily is the evidence-based maintenance dose for women ≥65 years 3, 5, 2
• This dose achieves the target serum 25-OH vitamin D level of ≥30 ng/mL, which is optimal for bone health and fracture prevention 3, 4
• Higher doses (≥800 IU/day) reduce hip fracture risk by 30% and nonvertebral fractures by 14% in adults ≥65 years 1, 3, 4

Calcium Co-Administration

Calcium supplementation is essential for optimal fracture prevention:

• 1,200 mg of elemental calcium daily is recommended for women ≥65 years 3, 5
• Calculate dietary calcium intake first, then supplement only to reach the total target of 1,200 mg daily 1
• Divide calcium doses into increments ≤600 mg for optimal absorption 3
• Combined vitamin D and calcium supplementation reduces hip fracture risk by 16% and overall fracture risk by 5% 3
• Calcium citrate may be preferred over calcium carbonate in patients taking proton pump inhibitors 3

Monitoring Strategy

Follow-up testing ensures adequate repletion:

• Recheck serum 25-OH vitamin D after 3 months of supplementation to confirm levels have reached ≥30 ng/mL 1, 3
• For daily dosing, measure after at least 3 months to allow plateau levels 1
• For intermittent dosing, measure just prior to the next scheduled dose 1
• Further monitoring should occur based on clinical judgment, particularly if dose adjustments are needed 1
• Calcium monitoring is only necessary in patients with conditions like primary hyperparathyroidism 1

Important Clinical Considerations

Key safety points and practical implementation:

• Vitamin D supplementation alone (without calcium) is less effective for fracture prevention than combined therapy 3
• Doses below 400 IU/day have not shown significant fracture reduction benefits 3
• The risk of kidney stones increases slightly with calcium supplementation (1 case per 273 women over 7 years) 1, 4
• At age 65, this patient can receive supplementation without baseline measurement if she has no musculoskeletal problems, cardiovascular disease, autoimmune disease, or cancer, though measurement is still preferred to guide dosing 1
• Adherence is critical—some patients may prefer weekly dosing over daily regimens 1

Target Outcomes

The goal is to achieve and maintain optimal vitamin D status:

• Target serum 25-OH vitamin D: ≥30 ng/mL for optimal bone health and fracture prevention 3, 4
• Minimum acceptable level: ≥20 ng/mL 3, 5
• Levels between 30-50 ng/mL are recommended by some guidelines for broader health benefits 3, 4