Fracture risk in patients treated for hyperthyroidism

Aim: To study fracture risk and risk factors for fractures in patients with hyperthyroidism. Design: Historical follow-up. Material and Methods: A total of 864 patients with diffuse toxic goiter (ICD 10: E05.0) or toxic nodular goiter (E05.2) were contacted through a self-administered questionnaire. Each respondent was compared to an age: (+/-5 years) and gender-matched control from a random sample of the background population who responded to the same questionnaire. Results: Among the patients 621 (72%) responded and of these 617 could be analyzed. Within the first 5 years before the diagnosis, the patients had the same fracture risk as the controls (RR = 1.2, 95% CI; 0.7-2.0). After the diagnosis, fracture risk was elevated among the patients (RR 1.7, 95% CI: 1.2-2.3), especially in the age group 50 years or older (RR = 2.2, 95% CI: 1.5-3.3). Fracture risk was elevated for fractures of the spine (RR = 8.9, 95% CI: 1.6-48.4), and the forearms (RR = 3.1, 95% CI: 1.6-6.2), but not at other skeletal sites. Treatment with radioactive iodine alone was associated with an increased fracture risk (OR = 2.7, 95% CI: 1.2-6.0), a risk that was not present in patients who, in addition to radioactive iodine, also had received methimazole (RR = 1.5, 95% CI: 0.7-3.2). Conclusions: Our study demonstrated an increased fracture risk in hyperthyroidism, a fracture risk that was present with radioactive iodine treatment alone, but not in subjects that had received both radioactive iodine and methimazole or other types of antithyroid therapy.