Thyroid-Stimulating Hormone Suppression Does Not Significantly Affect Bone Mineral Density

No significant differences in bone mineral density (BMD) were observed between patients with differentiated thyroid carcinoma (DTC) who received thyroid-stimulating hormone suppression (TSHS) and those who did not, according to a recent study.

Female gender, increasing age, and postmenopausal status are 3 common risk factors for decreased BMD and osteoporosis. But another factor that has been theorized to affect BMD is TSHS, which is used in DTC to reduce the risk of tumor recurrence after surgery and iodine-131.

However, use of TSHS has been speculated as a potential risk factor for BMD. In this study, investigators analyzed the BMD of postmenopausal women with DTC to determine if the use of TSHS can lead to increased bone loss in lumbar spine.

A total of 225 postmenopausal women with DTC were separated according to TSHS status: 154 patients were in the TSHS group and 71 patients in the nonsuppressed TSH group. Fourteen cases of follicular carcinoma and 211 papillary carcinomas were included in this study.

When assessing BMD of the lumbar spine at 6, 12, and 24 months, investigators found no significant differences in the BMD between the 2 groups. BMD in the TSHS group were 1.03±0.17, 1.04±0.14, and 1.03±0.15 at 6, 12, and 24 months, respectively. A reduction in BMD of 1.9% in the lumbar spine at the 2-year follow-up was observed compared with pre-TSHS treatment. BMD in the nonsuppressed TSH group were 0.98±0.16, 1.04±0.17, and 1.06±0.27 at 6,12, and 24 months, respectively. No significant differences were observed at any time interval (P = .89).

No significant differences were observed in the number of patients with osteopenia or osteoporosis at 6 and 12 months between the 2 groups (P = .65 and P = .72, respectively). However, at 24 months, the TSHS group (103/152) had significantly more patients with osteoporosis or osteopenia compared with the control group (32/68, P = .004). The difference in the prevalence of osteoporosis or osteopenia between the 2 groups was associated with the inhibition of osteoblastogenesis, osteoblast differentiation, and a reduction of osteoclast apoptosis. This correlates with previous findings that prolonged hyperthyroidism increases risk of osteoporosis and fractures.

Postmenopausal women with DTC on TSHS did not have significant differences in BMD compared with patients not on TSHS therapy. In addition, bisphosphates should be started at the beginning of TSHS treatment for patients with osteoporosis to increase BMD and prevent bone fractures, the researchers said. Future studies should be longer term and assess BMD in other areas such as the hip joint or the femoral bone.

Reference

Zhang P, Xi H, Yan R. Effects of thyrotropin suppression on lumbar bone mineral density in postmenopausal women with differentiated thyroid cancer. Onco Targets Ther. 2018;11:6687-6692. doi: 10.2147/OTT.S171282.