Common Questions
How is vitamin D deficiency treated and monitored?
Treatment. The initial treatment for vitamin D deficiency in patients with normal renal and liver function should be large doses of ergocalciferol, 50,000 IU once a week for eight weeks, in addition to 1500 mg of elemental calcium daily. For patients with malabsorption, larger doses of ergocalciferol (50,000 IU two to three times a week) may be necessary.
The vitamin D form of choice is ergocalciferol because:
- It is inexpensive and readily available.
- Even patients with malabsorption syndromes will absorb > 60 percent of vitamin D in this form (1).
Other forms of vitamin D might be more appropriate under certain clinical circumstances (see table below).
Monitoring. The parathyroid hormone (PTH) and 25-OH vitamin D levels should be checked 8 weeks after initiating therapy with ergocalciferol. Once the PTH and 25-OH vitamin D concentrations normalize, then the patient can be placed on a maintenance dose of vitamin D. The maintenance dose will vary depending on the underlying cause of vitamin D deficiency. Patients with a deficiency from lack of sun exposure and decreased dietary intake would require 1000 IU of cholecalciferol or ergocalciferol a day. An individual with malabsorption may require 25,000 to 50,000 IU (or more) per week. Anti-resorptive therapy for osteoporosis can then be initiated if indicated by bone densitometry.
If PTH and 25-OH vitamin D levels do not normalize with time in patients with gastrointestinal disorders, then ergocalciferol should be replaced with either oral calcitriol (1,25 dihydroxy vitamin D) which may help absorb calcium better on the luminal side of the gut or an injectable form of calcitriol. It is important to monitor the calcium levels frequently (every two weeks) when initiating the injectable form of calcitriol as it can cause hypercalcemia.
Osteopenia due to vitamin D deficiency should not be treated with an anti-resorptive medication such as calcitonin or a bisphosphonate. These medications could lead to severe hypocalcemia because the serum calcium level is being maintained at the expense of the calcium in the bones. There have not been any studies evaluating the effects of anti-resorptive medications in patients with vitamin D deficiency. The large studies addressing the effects of bisphosphonates on bone density excluded patients with hyperparthyroidism (2-4).
| Type of Vitamin D | Synonyms/Trade Names | Forms and Doses | Comment |
|---|---|---|---|
| Ergocalciferol |
|
|
Form used in vitamins and as food supplement. Derived from irradiated plant sterols. |
| Cholecalciferol |
|
Tablets: 400 IU to 1,000 IU | Fortification of food products |
| Calcifediol |
|
Capsules: 20 mcg, 50 mcg | Used in liver disease, anticonvulsant- induced osteomalacia. |
| Calcitriol |
|
|
Used in renal failure, nephrotic syndrome, and severe malabsorption syndromes. |
| Dihydro-tachysterol (synthetic analogue of vitamin D3) |
|
|
Used to correct idiopathic or postsurgical hypocalcemia due to its more rapid onset of action. |
Equivalent pharmacologic doses of various vitamin D preparations are ergocalciferol 1,250 mcg (50,000 IU), dihydrotachysterol 400 mcg, calcifediol 50 mcg, and calcitriol 1 mcg (5).
- Davies M, Mawer EB, Krawitt EL. Comparative absorbtion of vitamin D3 and 25-hydroxyvitamin D3 in intestinal disease. Gut 1980; 21: 287-92.
- Cummings SR, Black DM, Thompson DE, Applegate WB, et al. Effect of alendronate on risk of fracture in women with low bone density but without vertebral fractures: Results from the fracture intervention trial. JAMA 1998; 280: 2077-82.
- Liberman UA, Weiss SR, Broll J, Minne HW, Quan H, Bell NH, et al. The effect of oral alendronate on bone mineral density and the incidence of fractures in postmenopausal osteoporosis. The Alendronate Phase III Osteoporosis Treatment Study Group. N Engl J Med 1995; 333: 1437-43.
- Hosking D, Chilvers CED, Christiansen C, Ravn P, Wasnich R, Ross P, et al. Prevention of bone loss with alendronate in postmenopausal women under 60 years of age. Early Postmenopausal Intervention Cohort Study Group. N Engl J Med 1998; 338: 485-92.
- Kumar R, Riggs BL. Vitamin D in the therapy of disorders of calcium and phosphorus metabolism. Mayo Clin Proc 1981; 56(5): 327-33.