Vitamin D metabolism and the response to 1,25-dihydroxycholecalciferol in osteoporosis

Abstract

The metabolism of isotopicallylabelled cholecalciferol and the response to small doses of 1,25-dihydroxycholecalciferol (1,25-(OH)2D3) was studied in a group of women with osteoporosis presenting with crush vertebral fracture ’. No abnormality of vitamin D metabolism was detected. The administration of 1 μg 1,25-(OH)2D3 for between 8 and 20 days was associated with an increased intestinal absorption and urinary excretion of calcium but caused no improvement in calcium balance. There was a small but significant rise in serum calcium and phosphorus and a significant reduction in immunoassayable parathyroid hormone levels during treatment. It is concludedthat 1,25-(OH)2D3 is unlikely to be of value in the management of osteoporosis.