What is the recommended dosing for Vitamin D (Vit D) supplementation in the treatment of Vitamin D deficiency?

From the Guidelines

For vitamin D deficiency, the recommended treatment is typically 50,000 IU of vitamin D2 or D3 taken once weekly for 8-12 weeks, followed by a maintenance dose of 1,000-2,000 IU daily. This recommendation is based on the most recent and highest quality study available, which suggests that vitamin D3 may be more effective in raising 25(OH)D concentrations and maintaining those levels for a longer time when longer dosing intervals are employed 1.

Key Considerations

• The goal of treatment is to bring serum 25(OH)D levels to 30 ng/mL or higher, which is ideal for bone health 1.
• Vitamin D supplements should ideally be taken with meals containing some fat to enhance absorption, as vitamin D is fat-soluble.
• Severe deficiency may require longer treatment or higher doses under medical supervision.
• Vitamin D is essential for calcium absorption, bone health, immune function, and numerous other physiological processes, which is why correcting deficiency is important.
• Most people tolerate supplementation well, but excessive doses can lead to hypercalcemia, so follow-up monitoring is recommended.

Maintenance Therapy

• For maintenance therapy, most adults require 800-2,000 IU of vitamin D daily to prevent recurrence of deficiency 1.
• The choice of vitamin D2 or D3 may depend on the patient's preference and dietary restrictions, with vitamin D3 being preferred in countries where it is available 1.
• The need for calcium supplementation in addition to vitamin D depends on the patient's diet, with strict vegetarians potentially requiring additional calcium intake.

Monitoring and Follow-up

• Patients should have their vitamin D levels rechecked after completing the initial treatment phase to ensure they've reached the target range of 30-50 ng/mL.
• Follow-up monitoring is recommended to prevent excessive doses and potential toxicity, such as hypercalcemia.

From the FDA Drug Label

DOSAGE AND ADMINISTRATION THE RANGE BETWEEN THERAPEUTIC AND TOXIC DOSES IS NARROW. Vitamin D Resistant Rickets: 12,000 to 500,000 IU units daily. Hypoparathyroidism: 50,000 to 200,000 IU units daily concomitantly with calcium lactate 4 g, six times per day.

The dosing for Vitamin D deficiency is not explicitly stated in the provided drug label. However, for conditions related to vitamin D deficiency, such as Vitamin D Resistant Rickets and Hypoparathyroidism, the dosing ranges are:

• 12,000 to 500,000 IU units daily for Vitamin D Resistant Rickets
• 50,000 to 200,000 IU units daily for Hypoparathyroidism, concomitantly with calcium lactate It is crucial to note that dosage must be individualized under close medical supervision 2.

From the Research

Vitamin D Dosing for Deficiency

• The dosing of vitamin D for deficiency can vary depending on the individual's serum concentration of 25-hydroxyvitamin D, age, body mass index (BMI), and other factors 3, 4.
• A cumulative dose of at least 600,000 IU administered over several weeks may be necessary to replenish vitamin D stores in patients with documented deficiency 3.
• Single large doses of 300,000-500,000 IU should be avoided 3.
• A daily dose of 2000 IU (50 µg) of vitamin D3 may be sufficient to raise and maintain serum 25(OH)D concentrations above 50 nmol/L (20 ng/mL) and above 75 nmol/L (30 ng/mL) in >99% and >90% of the general adult population, respectively 5.
• However, some studies suggest that a maintenance dose of 2000 IU of vitamin D3 may not be enough to keep 25(OH)D levels above 30 ng/mL in all patients 6.

Factors Affecting Vitamin D Dosing

• Starting serum concentration of 25-hydroxyvitamin D 4
• Body mass index (BMI) 4
• Age 4
• Serum albumin concentration 4
• Race, although no clinically meaningful differences were found between white, black, and other racial groups 4

Calculating Vitamin D Dose

• A predictive equation can be used to calculate the dose of vitamin D needed to affect a given change in serum concentrations of 25-hydroxyvitamin D: Dose = [(8.52 - Desired change in serum 25-hydroxyvitamin D level) + (0.074 × Age) - (0.20 × BMI) + (1.74 × Albumin concentration) - (0.62 × Starting serum 25-hydroxyvitamin D concentration)]/(-0.002) 4.