Vitamin D Deficiency


Vitamin D deficiency is one of the most commonly encountered vitamin deficiencies in the developed world. It is more prevalent in the elderly, during winter months, and in northern latitudes, but is still surprisingly common–even in sunny southern Nevada. Vitamin D deficiency is seen more commonly in patients with digestive disorders (inflammatory bowel disease, celiac disease, malabsorption) and after gastric bypass or lap-band surgery.


Vitamin D deficiency is diagnosed by a measurement of 25 hydroxy vitamin D (25-OHD) in blood.

Vitamin D deficiency = 25-OHD < 20 ng/ml

Vitamin D insufficiency = 25-OHD 20–30 ng/ml

Normal Vitamin D levels = 20–100 ng/ml

Based on these criteria between 40 to 100 percent of elderly men and women are vitamin D deficient. Patients with metabolic bone diseases such as osteoporosis or osteopenia may experience suboptimal responses to therapy in the presence of inadequate levels of vitamin D.

Consequences of Vitamin D Deficiency

Low vitamin D levels are associated with osteoporosis and increased risk of falls and fractures. Even modest deficiency of vitamin D can cause elevation of parathyroid hormone (PTH) levels and secondary hyperparathyroidism. Chronic, severe vitamin D deficiency can cause osteomalacia (Rickets), low blood calcium and low phosphorus levels. There is strong scientific evidence linking low vitamin D levels with neurologic disorders, muscular weakness, cardiovascular disease, immune function and cancer.

Vitamin D Supplementation

In 1997, the National Academy of Sciences recommended a vitamin D intake of 400 IU/day for people 51–70 years of age and 600 IU/day for people 71 years and older. However, the average adult requires 800–1000 IU/day to maintain 25-OHD levels > 30 ng/mL.

Vitamin D3 (Cholecalciferol): the preferred vitamin D supplement, since this is the form of vitamin D found in humans. We generally recommend 1000–2000 IU daily, depending on individual patient circumstances. Higher doses may be required in patients with more advanced vitamin D deficiency. It is available as an over-the-counter supplement in varying doses.

Vitamin D2 (Ergocalciferol): a synthetic form of vitamin D2 that does not normally occur in humans, but is effective in treating vitamin D deficiency. It has approximately 1/3 of the potency of vitamin D3. It is available as a prescription and comes in capsules of 50,000 IU. It is generally taken only once weekly.


Inadequate levels of vitamin D are vey common. It is of utmost importance for patients with low bone density or metabolic bone diseases to have vitamin D levels optimized and appropriately monitored to enjoy a good response to medical therapy.