What is the best form of vitamin D for treating severe vitamin D deficiency?

From the Guidelines

Vitamin D3 (cholecalciferol) is the preferred form for treating severe vitamin D deficiency due to its greater efficacy in raising blood levels. For patients with serum 25(OH) D levels below 30 ng/mL, a common regimen is prescription vitamin D (ergocalciferol) 50,000 IU weekly for 8 weeks, followed by a recheck of the serum 25(OH) D level, with subsequent dosing based on the results 1. However, vitamin D3 could be more effective in raising 25(OH) D concentrations and maintaining those levels for a longer time when longer dosing intervals are employed 1.

Some key points to consider when treating severe vitamin D deficiency include:

• The goal of treatment is to bring serum 25(OH) D levels to 30 ng/ml (75 nmol/L) or higher 1
• 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
• Calcium supplementation may also be recommended alongside vitamin D therapy to support bone health, as vitamin D is essential for calcium absorption 1
• Current expert opinion on supplementation for adults older than age 50 is 1200 mg of calcium (from all sources) and 800 to 1000 IU of vitamin D daily 1

It's essential to monitor serum 25(OH) D levels regularly to adjust the treatment regimen as needed and prevent toxicity. Additionally, taking vitamin D supplements with a meal containing some fat improves absorption since vitamin D is fat-soluble.

From the FDA Drug Label

PRECAUTIONS General Vitamin D administration from fortified foods, dietary supplements, self-administered and prescription drug sources should be evaluated. Adequate dietary calcium is necessary for clinical response to vitamin D therapy. Caution Adequate dietary calcium is necessary for response to vitamin D therapy.

The best form of vitamin D for treating severe vitamin D deficiency is not explicitly stated in the provided drug labels. However, cholecalciferol (PO) and ergocalciferol (IM) are two forms of vitamin D mentioned.

• Cholecalciferol (PO) is an oral form of vitamin D, and its label provides more detailed information about precautions and potential side effects 2.
• Ergocalciferol (IM) is an intramuscular form of vitamin D, with a label that emphasizes the importance of adequate dietary calcium for response to therapy 3. Since the labels do not directly compare the effectiveness of these two forms for treating severe vitamin D deficiency, no conclusion can be drawn about which one is better.

From the Research

Treatment Options for Severe Vitamin D Deficiency

• Severe vitamin D deficiency can be treated with various forms of vitamin D, including cholecalciferol (vitamin D3) and calcifediol 4, 5.
• Cholecalciferol is considered the form of vitamin D of choice for exogenous supplementation, as it has more scientific evidence with positive results than calcifediol in musculoskeletal diseases 4.
• Calcifediol may be reserved for patients with liver failure or severe intestinal malabsorption syndromes 4.

Dosage and Administration

• The goal of treatment is to normalize vitamin D levels to relieve symptoms and decrease the risk of fractures, falls, and other adverse health outcomes 6.
• A cholecalciferol loading dose of 100,000 to 200,000 IU can increase mean serum 25-hydroxyvitamin D levels by 29-69 nmol/l 7.
• Daily doses of 7000 IU or intermittent doses of 30,000 IU/week can be considered for a prolonged time as prophylactic or maintenance doses, mainly in obese patients, patients with liver disease, and patients with malabsorption syndromes 8.
• Intermittent doses of 30,000 IU twice weekly or 50,000 IU per week can be considered for a 6-8-week period for the treatment of possible vitamin D deficiency without assessment of 25-hydroxyvitamin D in these groups 8.

Comparison of Cholecalciferol and Calcifediol

• Oral calcifediol results in a more rapid increase in serum 25-hydroxyvitamin D compared to oral cholecalciferol 5.
• Oral calcifediol is more potent than cholecalciferol, so that lower dosages are needed 5.
• Calcifediol has a higher rate of intestinal absorption, which may have important advantages in case of decreased intestinal absorption capacity due to a variety of diseases 5.