Vitamin D is a fat-soluble vitamin used for preventing osteoporosis in men and women, muscle weakness, enhancing immune function, preventing autoimmune diseases, multiple sclerosis, rheumatoid arthritis, chronic obstructive pulmonary disease (COPD), asthma, bronchitis, and cancer. It is also used orally for rickets, influenza, preventing falls and fractures in people at risk for osteoporosis, corticosteroid-induced osteoporosis, osteomalacia, anticonvulsant-induced osteomalacia, renal osteodystrophy, osteitisfibrosa in people on dialysis, hepatic osteodystrophy, and osteogenesisimperfecta. Vitamin D is also used for preventing and treating hypocalcemia and tetany in premature infants’ bone disorders in people with familial hypophosphatemia, hypophosphatemia associated with Fanconi syndrome, and hypocalcemia associated with postoperative or idiopathic hypoparathyroidism or pseudohypoparathyroidism. Other uses include plaque-type psoriasis, actinic keratosis, lupus vulgaris, squamous cell carcinomas, vitiligo, scleroderma, myelodysplastic syndrome, periodontal disease, hypertension, hyperlipidemia, cardiovascular disease, obesity, and diabetes. Vitamin D is also used orally to treat severe proximal myopathy associated with vitamin D deficiency or myopathy associated with the use of HMG-CoA reductase inhibitors (statin-induced myopathy), and to maintain bone density in prostatic cancer patients at risk for osteoporosis when treated with luteinizing hormone-releasing hormone analogue (LHRH-a).