Vitamin D is used for preventing and treating rickets, a disease that is caused by not having enough vitamin D (vitamin D deficiency) Vitamin D is also used for treating weak bones (osteoporosis), bone pain (osteomalacia), bone loss in people with a condition called hyperparathyroidism Vitamin D is used in an inherited disease (osteogenesis imperfecta) in which the bones are especially brittle and easily broken Vitamin D is used for preventing falls and fractures in people at risk for osteoporosis, and preventing low calcium and bone loss (renal osteodystrophy) in people with kidney failure