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.