Long-term effects of small doses of 1,25-dihydroxycholecalciferol in renal osteodystrophy.

An oral dose of 0.5 microgram of 1,25-dihydroxycholecalciferol (1,25-[OH]2D3) and 4 g of calcium carbonate was given daily to two dialysed patients and three undialysed patients in chronic renal failure with renal osteodystrophy. Treatment was given for 4-16 months. Intestinal calcium absorption became normal in all five patients. Plasma alkaline phosphatase, hydroxyproline, and immunoreactive parathyroid hormone were considerably reduced in all of the patients and in four of them these values were restored to normal. Bone histology was improved in all patients after treatment with 1,25-(OH)2D3. As well as a dramatic improvement in bone mineralisation, there was remodeling of trabecular architecture and a decrease in fibrosis in patients with initial parathyroid overactivity.