1. Vitamin D deficiency is diagnosed by measuring a total serum 25(OH)D of <10 ng/ml.
2. The clinical significance and laboratory cut-off of 25(OH)D for vitamin D insufficiency is controversial.
3. Vitamin D supplementation can be accomplished with food, sunlight, and over-the-counter or prescription vitamin D preparations.
4. The maintenance dose of oral vitamin D is controversial, although 1000-2000 IU D3per day appears to be safe. There is risk to taking too much vitamin D supplementation.
