title: Long-term treatment of osteoporosis with 24,25 dihydroxycholecalciferol.
abstract: Five patients with involutional osteoporosis were treated with 24,25 dihydroxycholecalciferol (24,25-(OH)2D3) for 6 months, in doses sufficient to double plasma levels at that time. Dietary calcium absorption transiently improved by nearly 2 mmol Ca per day at 2 weeks, but this effect was lost by 6 months. The calcium and phosphate balances followed the trends in calcium absorption. Only twenty-five dihydroxyvitamin D levels changed little. Histomorphometric and kinetic indices of new bone formation and bone blood flow remained stable but there was an increase in urine hydroxyproline at 6 months, which was of borderline statistical significance. Treatment at this dosage of 24,25(OH)2D3, which increased plasma levels within the physiological range, conferred no measurable long-term benefit on our patients. Larger doses, or combination therapy, may warrant further clinical evaluation in osteoporosis.
mesh_terms: D015650:24,25-Dihydroxyvitamin D 3; D002118:Calcium / Q000378:metabolism; D004100:Dihydroxycholecalciferols / Q000097:blood / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D010024:Osteoporosis / Q000188:drug therapy*; D013997:Time Factors
chemical_list: D004100:Dihydroxycholecalciferols; D015650:24,25-Dihydroxyvitamin D 3; D002118:Calcium