[Clinical study on bone mineral mass in metabolic bone disorders--I-125 photon absorptiometry]

Changes in bone mineral mass were investigated by 125I-photon absorptiometry in 5 groups of patients; postmenopausal osteoporosis (n = 50), after partial or total gastrectomy (n = 54), thyroid disorders (n = 28), parathyroid disorders (n = 6) and healthy subjects (n = 214) as control. Radial bone mineral content (BMC) was measured at the distal 1/3 and 1/6 sites of the radius and the densitometric patterns were analized . The results obtained were as follows: Age variation in bone mineral mass and bone mineral change in pathological status were more sensitively detectable at the distal 1/6 site of the radius (predominantly trabecular) than the distal 1/3 site of the radius (predominantly cortical). In osteoporosis there was a diminution in radial 1/6 BMC and a significant decrease of radial trabecular bone index ( RTBI ) estimated from densitometric patterns, as compared with age-matched control. Sequential changes of bone mineral mass were evaluated during the treatment. There was no significant change in bone mineral mass during the first 3 months of 1 alpha-OH-D3 administration. Bone mineral mass then decreased about 20% in radial 1/6 BMC in the course of the treatment. An increase in bone mineral mass at the distal 1/6 site of the radius was revealed at 1 year treatment with 1 alpha-OH-D3. But at the distal 1/3 site of the radius only a little change in bone mineral mass was recognized during the treatment. Total gastrectomy caused a significant deficit of radial BMC as compared to partial gastrectomy. 1 alpha-OH-D3 was also effective on bone mineral loss after gastrectomy. Loss of radial 1/6 BMC occurred in hyperthyroidism (high turn over osteoporosis) but not in hypothyroidism. Striking bone mineral loss was observed in hyperparathyroidism, which recovered after surgical treatment.