Diseases caused by disturbances in the calcium metabolism in consequence of reduced endogenous production of 1.25-dihydroxyvitamin D3. Renal osteodystrophy, postoperative or idiopathic hypo-parathyroidism, pseudohypoparathyroidism, as an adjunct to the management of tertiary hyperparathyroidism, vitamin D-resistant rickets or osteomalacia, vitamin D-dependent rickets, neonatal hypocalcaemia or rickets, malabsorption of calcium, osteoporosis, malabsorptive and nutritional rickets, and osteomalacia.