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

Abstract

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.

Keywords: bone mineral density; differentiated thyroid carcinoma; thyrotropin suppressive therapy; trabecular bone score.

FIGURE 1

Baseline and end TBS scores according to the follow‐up of TSH suppression in patients of Group I (5‐10 years) and Group II (>10 years). Upper and lower lines indicates limits of normal, partially degraded and degrades TBS scores values

FIGURE 2

TBS scores of patients with DTC according to the degree of TSH suppression. Upper and lower lines indicates limits of normal, partially degraded and degrades TBS scores values