What is used for repleting vitamin D?

From the Guidelines

Vitamin D repletion typically involves using oral supplements containing vitamin D3 (cholecalciferol), which is generally preferred due to its greater efficacy in raising serum vitamin D levels. When repleting vitamin D, the choice between vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol) is important, with vitamin D3 being more effective in raising 25(OH)D concentrations and maintaining those levels for a longer time when longer dosing intervals are employed 1. The most recent and highest quality study suggests that vitamin D3 is the preferred form for supplementation 2.

Key Considerations for Vitamin D Repletion

• For moderate deficiency, a common regimen is 50,000 IU of vitamin D3 weekly for 8-12 weeks, followed by maintenance therapy of 1,000-2,000 IU daily.
• For severe deficiency, higher doses may be needed initially, and maintenance dosing typically ranges from 800-2,000 IU daily depending on individual factors.
• Vitamin D supplements are available over-the-counter in various strengths and formulations, including tablets, capsules, and liquid drops.
• Some patients may require prescription-strength supplements for significant deficiency.
• Vitamin D is fat-soluble, so taking it with a meal containing some fat improves absorption.
• Repletion is important because vitamin D plays crucial roles in calcium absorption, bone health, immune function, and other physiological processes.
• Blood levels should be monitored during repletion to ensure adequate dosing and avoid toxicity, as vitamin D toxicity (hypercalcemia, hyperphosphatemia, and activation of bone resorption) is uncommon but may occur with daily doses of more than 50,000 IU per day that produce 25(OH)D levels larger than 150 ng/mL 1.

Recommendations for Vitamin D Intake

• The Institute of Medicine recommends daily dietary vitamin D intake of 600 IU in adults aged 18 to 70 years and 800 IU in adults older than 70 years 3, 2.
• The Endocrine Society and Osteoporosis Society also propose guidelines for vitamin D deficiency, with conservative definitions defining vitamin D deficiency as levels of 25(OH)D3 < 20 ng/ml (< 50 nmol/L), and vitamin D insufficiency as 20 – 30 ng/ml (50 – 75 nmol/L) 2.
• It is essential to note that the use of the terms “daily” and “per day” in these recommendations may give the false impression that a day without sunshine requires a dose of supplement, and that vitamin D-hormones may not require daily, weekly or even monthly replenishment 2.

From the FDA Drug Label

Health Claims DIETARY SUPPLEMENT Vitamin D3 50,000 IU is essential for absorption of calcium and necessary for healthy bones and a healthy immune system. Caution Adequate dietary calcium is necessary for response to vitamin D therapy.

When repleting vitamin D, we use Vitamin D3 (cholecalciferol) or Vitamin D2 (ergocalciferol).

• Cholecalciferol is used as it is essential for absorption of calcium and necessary for healthy bones and a healthy immune system 4.
• Ergocalciferol is also used for vitamin D repletion, with the caution that adequate dietary calcium is necessary for response to vitamin D therapy 5.

From the Research

Vitamin D Supplementation

When replenishing vitamin D, the following options are used:

• Vitamin D3 (cholecalciferol) in doses ranging from 5000 to 50,000 IUs/day, as seen in a study published in 2019 6
• A single oral dose of 300,000 IU vitamin D3, as described in a 2009 study 7
• Daily doses of 800-5000 IU/day, which have been shown to improve musculoskeletal health 8
• Daily or weekly "high doses" of cholecalciferol, such as 7000 IU daily, 30,000 IU per week or twice weekly, and 50,000 IU weekly, which have been studied for the prevention and treatment of vitamin D deficiency in obese or multi-morbidity patients 9

Dosage Considerations

The choice of dosage depends on various factors, including:

• The severity of vitamin D deficiency
• The patient's age, weight, and medical condition
• The presence of other health conditions, such as kidney or liver disease
• The use of other medications that may interact with vitamin D

Safety and Efficacy

Studies have shown that vitamin D supplementation is generally safe and effective in replenishing vitamin D stores, with few reported adverse events 6, 7, 8, 9. However, high doses of vitamin D should be used with caution and under medical supervision to avoid potential side effects, such as hypercalcemia.