Abstract
Vitamin D deficiency, insufficiency, and sufficiency are categories used to describe the nutritional status of vitamin D and are defined by the level of serum 25 hydroxyvitamin D (25OHD). The changes in serum vitamin D are a continuum with insufficiency and osteoporosis at one end of the spectrum and severe deficiency and osteomalacia at the other end. Controversy has arisen over the level of serum 25OHD that defines vitamin D insufficiency and deficiency. Severe vitamin D deficiency causes malabsorption of calcium and phosphorus from the diet, secondary hyperparathyroidism and defective mineralization of bone leading to osteoporosis and osteomalacia. The two major natural sources of vitamin D are sunlight and diet. Vitamin D deficiency and insufficiency is an important clinical problem in all parts of the world. Screening of high-risk groups for low serum 25OHD and then treatment with vitamin D 600-800 IU and calcium 500-750 mg daily can reduce fractures.