Trabecular bone deterioration in differentiated thyroid cancer: Impact of long-term TSH suppressive therapy.

BACKGROUND: Conflicting results has been reported regard osteoporosis and fractures in patients with Differentiated Thyroid Cancer (DTC). Our objective was to evaluate the long-term effects of TSH suppression therapy with Levothyroxine (LT4) on trabecular bone score (TBS) and bone mineral density (BMD) in females with DTC after thyroidectomy. METHODS: About 145 women with resected DTC and receiving long-term TSH therapy, were stratified according to the degree of TSH suppression. Mean duration of follow-up was 12.3 ± 6.1 years. BMD and TBS, were assessed using dual-energy X-ray absorptiometry (DXA) and TBS iNsight (Med-Imaps), at baseline (1-3 months after surgery) and at the final study visit. RESULTS: In patients stratified by duration of TSH suppression therapy (Group I, 5-10 years; Group II, >10 years), slight increases from baseline TSH levels were observed. Significant decreases in LS-BMD and FN-BMD were seen in patients after >10 years. TBS values were lower in Groups I (1.289 ± 0.122) and II (1.259 ± 0.129) compared with baseline values (P = .0001, both groups). Regarding the degree of TSH suppression, TBS was significantly reduced in those with TSH < 0.1 µU/mL (P = .0086), and not in patients with TSH suppression of 0.1.-0.5 or >0.5 µU/mL. CONCLUSIONS: We found deterioration of trabecular structure in patients with DTC and TSH suppression therapy below 0.1 µU/mL and after 5-10 years of follow-up. Significant changes in BMD according to TSH levels were not observed. Trabecular Bone Score is a useful technique for identifying thyroid cancer patients with risk of bone deterioration.

Low trabecular bone score in postmenopausal women with differentiated thyroid carcinoma after long-term TSH suppressive therapy.

The effect of thyroid suppression therapy (TST) on trabecular bone scores (TBS) and bone mineral density (BMD) in thyroidectomized women with differentiated thyroid carcinoma (DTC) on long-term follow-up is presently not conclusive. PATIENTS AND METHODS: We carried out a study in 61 premenopausal and 84 postmenopausal Caucasian women with DTC. Serum biochemistry, bone markers, TBS, BMD, and bone fractures were evaluated 1-3 months post surgery and after a median follow-up of 10 years. RESULTS: In the final study, patients belonged to Group I Premenopausal (n = 14) who remained in this status; Group II Premenopausal who became postmenopausal (n = 47); Group III patients who were and continued as postmenopausal (n = 84). Baseline premenopausal patients had a normal TBS mean value of 1.39 ± 0.14 significantly higher than that found in postmenopausal 1.31 ± 0.12 (p = 001). In the final study, premenopausal patients continued to have a normal TBS of 1.46 ± 0.08 compared to the significantly lower value of postmenopausal patients 1.25 ± 0.11 (p = 0.0009). Lumbar BMD (L-BMD) loss after the long-term study was significant in Group II (0.99 g/cm2 ± 0.13 vs. 0.91 ± 0.12 g/cm2, p < 0.0001) and there was a slight, but not significant, bone loss in Group I (1.00 ± 0.12 vs. 0.98 ± 0.11, p = 0.1936) and in Group III (0.86 ± 0.12 vs. 0.84 ± 0.15, p = 0.1924) compared with baseline values. CONCLUSION: Longer-term suppression therapy in female patients with DTC did not increase significantly the risk of bone loss, although we found in postmenopausal patients deterioration of bone microarchitecture. TBS study should be considered in the evaluation of postmenopausal DTC patients on long-term DTC for the evaluation of the risk of fractures.