Bone mineral density and bone structure in primary udhypoparathyroidism

摘要

Since parathyroid hormone has dual properties on bone, bothudcatabolic and anabolic, it is interesting to review how the boneudmineral density and structure change in patients with chronicudhypoparathyroidism. Others and we have demonstrated consistentlyudthat the state of chronic hypoparathyroidism is associatedudwith increased BMD, most notably at the spine. Those with idiopathicudhypoparathyroidism have a similar degree of increase inudBMD as those with postthyroidectomy hypoparathyroidism.udBoth groups also have significantly lower level of biochemicaludmarkers such as osteocalcin, bone-specific alkaline phosphataseudactivity and urinary resorption markers as comparedudwith controls. This reflects the low rate of bone remodeling andudimplies a significant reduction in “birth rate” of bone modelingudunits and prolongs the “life span” of the basic structural unit. Itudtherefore allows for more complete secondary mineralization.udThe reduction in bone remodeling is further confirmed by boneudhistomorphometry. The observed effect on BMD is likely a resultudof the combined effects of decreased bone resorption due to hypoparathyroidismudand the improvement in bone mineralizationudas a result of continuous treatment with calcitriol and calcium