Used for the prevention and treatment of rickets or osteomalacia, and to manage hypocalcemia associated with hypoparathyroidism or pseudohypoparathyroidism. Also used for the treatment of vitamin D dependent rickets, rickets or osteomalacia secondary to long-term high dose anticonvulsant therapy, early renal osteodystrophy, osteoporosis (in conjunction with calcium), and hypophosphatemia associated with Fanconi syndrome (with treatment of acidosis).