Hip fractures and the thyroid: a case-control study.

ABSTRACT

OBJECTIVE: To investigate the prevalence of thyroid illness - especially hyperthyroidism - and exposure to thyroid hormones in patients with hip fracture. DESIGN: A case-control study. SETTING: Two surgical/orthopaedic hospital units and 22 facilities for the aged in a moderately iodine-deficient region of Germany. SUBJECTS: A total of 116 postmenopausal females with hip fracture and 402 postmenopausal female controls. MAIN OUTCOME MEASURES: Hip fracture; thyroid disease confirmed by measurement of serum thyrotropin, total and free thyroxine and triiodothyronine; history of thyroid disease and thyroid medication obtained by a questionnaire. RESULTS: Of the hip fracture patients 4.3% had overt untreated hyperthyroidism, and 6.9% gave a history of past hyperthyroidism (total, 11.2%). The corresponding figures for the controls were 2.0 and 2.7%, respectively (total, 4.7%). 7.8% of the cases had been exposed to levo-thyroxine for 3-29 years, compared to 11.2% of the controls. The odds ratio for hyperthyroidism (present and past) was 2.5 (1.2-5.3, 95% confidence interval), and the odds ratio for levo-thyroxine exposure was 0.67 (0.32-1.41) in the hip fracture patients. CONCLUSIONS: Hyperthyroidism is found 2.5-fold more often in hip fracture patients than in controls. Hence, hyperthyroidism appears to be a significant risk factor for hip fracture and should be investigated by clinical and, when necessary, laboratory means in hip fracture patients. In contrast, no increased risk for hip fracture could be detected after exposure to levothyroxine.