Fractures following thyroidectomy in women: a population-based cohort study.

Hip fracture risk has been associated with hyperthyroidism and thyroidectomy in men and with hyperthyroidism in women, but the influence of thyroidectomy on fracture risk in women has not been adequately addressed. The 630 Rochester, MN women who underwent thyroidectomy in 1950-1974 were followed subsequently for 12,804 person-years (retrospective cohort study) during which 601 fractures were observed. Relative to incidence rates in the community, there was no increase in overall fracture risk (standardized incidence ratio [SIR] 0.9; 95% confidence interval [CI] 0.8-1.00). No increase was seen in limb fractures generally or in distal forearm fractures specifically (SIR 1.1, 95% CI 0.8-1.4). There was a modest but statistically significant increase in the risk of hip fractures following thyroidectomy (SIR 1.3, 95% CI 1.01-1.8), but much greater increases were apparent in the risk of subsequent fractures of the ribs, spine, and pelvis. There was almost a threefold increase in vertebral fractures (SIR 2.8, 95% CI 2.3-3.3), but the excess was mostly observed long after the original operation and may be attributable to ascertainment bias. Fracture risk was associated with advancing age and with the presence of one or more of the diseases that have been associated with secondary osteoporosis but not with a history of hyperthyroidism, extent of thyroid surgery, or subsequent use of thyroid replacement therapy. Thus, with the exception of some fractures of the axial skeleton, which might have been more completely diagnosed among affected women, there was no increase in fracture risk among women following thyroidectomy performed mainly for adenoma or goiter.