Vitamin D: Important for Prevention of Osteoporosis, Cardiovascular Heart Disease, Type 1 Diabetes, Autoimmune Diseases, and Some Cancers

Michael F. Holick, MD, PHD


South Med J. 2005;98(10):1024-1027. 

In This Article

Evaluation and Treatment of Vitamin D Deficiency

Measurement of 25(OH)D is the only means to determine whether a patient is vitamin D deficient or sufficient. The measurement of 1,25(OH)2D is not only useless, but can mislead the physician because it is often either normal or even elevated when a patient is vitamin D deficient and has secondary hyperparathyroidism. Most commercial laboratories report that a 25(OH)D less than 10 ng/mL is synonymous with vitamin D deficiency. Most experts recommend that less than 20 ng/mL should be designated as vitamin D deficiency.[28,29,30] To maintain a healthy level of 25(OH)D, the recommendation is that it should be above 30 ng/mL.

The easiest way to correct vitamin D deficiency is to fill up the empty vitamin D tank by giving the patient an oral dose of 50,000 IU of vitamin D once per week for 8 weeks. To maintain vitamin D sufficiency, the patient should receive either 50,000 IU of vitamin D once or twice per month thereafter. There is an intramuscular form of vitamin D that is usually not very bioavailable and can cause significant discomfort; therefore it is not recommended. However, in Europe, intramuscular injection of 500,000 IU of vitamin D twice per year has appeared to be effective in preventing vitamin D deficiency.

A multivitamin containing 400 IU of vitamin D is inadequate to satisfy the body's requirement.[32] It is estimated that at least 1,000 IU of vitamin D per day is needed to satisfy the body's requirement.[31,33]


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