Search

Background: An increased or normal serum TSH concentration, despite elevated thyroid hormone levels, is observed in resistance to thyroid hormone (RTH) and TSH-secreting adenomas (TSHomas). When coexistent with a differentiated thyroid cancer (DTC), maintenance of a suppression of TSH is challenging., Objectives: The aim of the study was to discuss the pitfalls arising from the failure to suppress TSH secretion in DTC and the strategies for proper treatment of DTC in association with RTH and TSHoma., Methods: Four unusual cases of DTC associated with TSHoma (2 cases), RTH (1 case), and an elevated TSH of unknown etiology (1 case) are presented, and the literature is reviewed., Results: Although a persistent mild TSH elevation may not be a risk factor for the development of DTC, it represents an important problem during the treatment of DTC. Aggressive treatment options should be applied in the proper order to prevent tumor recurrence and persistence in the absence of ideal TSH suppression., Conclusions: Although there is no agreed consensus regarding the management of DTC in the presence of persistent hyperthyrotropinemia, complete tumor removal followed by radioablation and attempts to reduce the serum TSH to the lowest tolerable level are recommended. The outcomes in the reported cases have not been unfavorable, despite the persistence of nonsuppressed TSH.

Forty-eight patients with differentiated thyroid cancer (DTC), who had no evidence of tumor recurrence or metastases on studies such as radioiodine scanning, neck ultrasonography, and with thyrotropin (TSH) and thyroglobulin (Tg) levels less than 1 mU/L and 5 ng/mL, respectively, were included in the study. The mean age was 43 +/- 12 years (range 15-65) and all were receiving levothyroxine (LT4) treatment with a mean dose of 184 +/- 46 microg daily. Patients were divided into two groups; group A included patients that had baseline TSH levels of 0.4 mU/L or more, and group B patients had baseline TSH levels of less than 0.4 mU/L. LT4 doses for all patients were increased, and serum TSH and Tg measurements were reevaluated after 2 months of dose increments. The mean TSH of group A (patients with baseline TSH levels > or = 0.4 mU/L) decreased from 0.67 +/- 0.28 mU/L to 0.16 +/- 0.08 mU/L (p < 0.001), but mean serum Tg level showed no change after dose increments (2.92 +/- 1.36 ng/mL vs. 3.59 +/- 0.93 ng/mL at the second month; p > 0.05). Similar results were also observed in group B (patients with baseline TSH levels < 0.4 mU/L). Mean TSH level decreased from 0.26 +/- 0.07 mU/L to 0.1 +/- 0.05 mU/L (p = 0.006), but no decrease occurred in mean Tg level (3.0 +/- 1.16 ng/mL vs. 3.3 +/- 1.03 ng/mL; p > 0.05). The patients' data were reevaluated according to second-month TSH levels. Patients with a TSH level between 0.11 to 0.4 mU/L were set as "final TSH > 0.1 group," and patients with a TSH level equal or less than 0.1 mU/L were set as "final TSH < or = 0.1 group," and baseline and second-month Tg levels were assessed. The mean second month Tg levels did not differ in these two patient groups (3.7 +/- 0.74 ng/mL for final TSH > 0.1 group vs. 3.3 +/- 1.2 ng/mL for final TSH < or = 0.1 group; p > 0.05). No difference could be found between initial and second-month Tg levels in both groups (2.8 +/- 1.4 ng/mL vs. 3.7 +/- 0.74 ng/mL in final TSH > 0.1 group and 3.11 +/- 1.1 ng/mL vs. 3.3 +/- 1.2 in final TSH < or = 0.1 group; p > 0.05). In conclusion, these results indicate that serum Tg levels cannot be suppressed by maximal TSH suppression in tumor-free DTC patients. The suppression of TSH to less than 0.1 mU/L seems not to be necessary in most patients who have no evidence of active disease.

Introduction. Our goal was to evaluate and compare the diagnostic utility of thyroid hormone withdrawal (THW) and recombinant thyroid-stimulating hormone (rhTSH) methods in detecting recurrence/persistence (R/PD) of differentiated thyroid carcinoma (DTC). Methods. The study included 413 patients with DTC who underwent total thyroidectomy and had remnant ablation. DxWBS, s-Tg levels, R/PD were evaluated retrospectively. A s-Tg level=2 ng/mL was considered as "positive s-Tg". Results. DxWBS and s-Tg levels were evaluated with rhTSH in 116 and THW in 297 subjects, respectively. The sensitivity and specificity of "positive s-Tg" for R/PD in THW group were 77.3% and 92.7%, with 90.3% accuracy, respectively. The sensitivity and specificity of "positive s-Tg" for R/PD in rhTSH group were 58.8% and 100% with 93.9 % accuracy, respectively. An uptake outside thyroid bed at WBS showed a sensitivity of 17.1%, specificity of 100% for R/PD with 89.4% accuracy in THW group. An uptake outside thyroid bed at WBS showed a sensitivity of 7.7%, specificity of 100% for R/PD with 88.8% accuracy in rhTSH group. Conclusion. Method of TSH stimulation did not influence the reliability of DxWBS. The "positive s-Tg level" had a higher sensitivity with THW when compared to rhTSH in detecting R/PD. [ABSTRACT FROM AUTHOR]