The effect of thyroid hormone on skeletal integrity

Background: Thyroid disease and osteoporosis are common problems often mana ged by primary care physicians, Despite many studies, confusion still exist s about the effect of thyroid hormone on skeletal health. Purpose: To review evidence on. the effect of thyroid hormone(from hyperthy roidism, exogenous or endogenous suppression of thyroid-stimulating hormone [TSH], and thyroid hormone replacement therapy) on skeletal integrity. Data Sources: A MEDLINE search of papers published between 1966 and 1997. Data Selection: Cross-sectional studies, longitudinal studies, and meta-ana lyses that had appropriate control groups (patients matched for age, sex, a nd menopausal status), made comparisons with established databases, or defi ned thyroid state by TSH level or thyroid hormone dose were reviewed. Data Extraction and Synthesis: Data synthesis was not straightforward becau se of changes in doses and types of thyroid hormone preparations; changes i n definitions of thyroid hormone replacement therapy and suppressive therap ies; problems with study design; differences in skeletal sites assessed (hi p, spine, forearm, or heel) and techniques used to measure bone mineral den sity; and inclusion of heterogenous and changing thyroid disease states. Ov erall, hyperthyroidism and use of thyroid hormone to suppress TSH because o f thyroid cancer, goiters, or nodules seem to have an adverse effect on bon e, especially in postmenopausal women; the largest effect is on cortical bo ne. Thyroid hormone replacement seems to have a minimal clinical effect on bone. Conclusion: Women with a history of hyperthyroidism or TSH suppression by t hyroid hormone should have skeletal status assessed by bone mineral densito metry, preferably at a site containing cortical bone, such as the hip or fo rearm.