Effect of thyrotropin suppression therapy on bone microarchitecture in postoperative patients with differentiated thyroid cancer.

[BACKGROUND] One of the main hazards of long-term subclinical hyperthyroidism is the induction and acceleration of osteoporosis. The aim of this study was to investigate the effect of postoperative thyrotropin (TSH) suppression therapy on bone microarchitecture in differentiated thyroid cancer (DTC).

[METHODS] This is a cross-sectional study involving 67 adult patients with DTC after surgery. Among them, 35 patients were currently undergoing TSH suppression therapy. The remaining 32 patients currently had normal thyroid function, but had a prior history of TSH suppression therapy. By utilizing high-resolution peripheral quantitative computed tomography (HR-pQCT) to scan the distal radius and tibia, the three-dimensional structure of the skeleton was reconstructed and measurements of bone microarchitecture were obtained.

[RESULTS] Compared with age- and gender-matched controls, the 35 patients with DTC under TSH suppression therapy had lower total volumetric bone mineral density and decreased cortical thickness at the distal radius. In the subgroup of 30 female patients, the total volumetric bone mineral density, cortical thickness, and trabecular thickness of distal radius were found to be lower than those of the control group. There were 15 postmenopausal women included in the study. Whether they were under TSH suppression therapy or their thyroid function returned to normal, they had lower cortical volumetric bone mineral density at the distal radius. Patients under TSH suppression therapy also had decreased cortical thickness at the distal radius, and lower cortical volumetric bone mineral density at the distal tibia.

[CONCLUSIONS] The subclinical hyperthyroidism caused by TSH suppression therapy may impact bone microarchitecture, especially in the cortical region at the distal radius.