Failure of radioactive iodine in the treatment of hyperthyroidism.

BACKGROUND: Persistent or recurrent hyperthyroidism after treatment with radioactive iodine (RAI) is common and many patients require either additional doses or surgery before they are cured. The purpose of this study was to identify patterns and predictors of failure of RAI in patients with hyperthyroidism. METHODS: We conducted a retrospective review of patients treated with RAI from 2007 to 2010. Failure of RAI was defined as receipt of additional dose(s) and/or total thyroidectomy. Using a Cox proportional hazards model, we conducted univariate analysis to identify factors associated with failure of RAI. A final multivariate model was then constructed with significant (p < 0.05) variables from the univariate analysis. RESULTS: Of the 325 patients analyzed, 74 patients (22.8 %) failed initial RAI treatment, 53 (71.6 %) received additional RAI, 13 (17.6 %) received additional RAI followed by surgery, and the remaining 8 (10.8 %) were cured after thyroidectomy. The percentage of patients who failed decreased in a stepwise fashion as RAI dose increased. Similarly, the incidence of failure increased as the presenting T3 level increased. Sensitivity analysis revealed that RAI doses <12.5 mCi were associated with failure while initial T3 and free T4 levels of at least 4.5 pg/mL and 2.3 ng/dL, respectively, were associated with failure. In the final multivariate analysis, higher T4 (hazard ratio [HR] 1.13; 95 % confidence interval [CI] 1.02-1.26; p = 0.02) and methimazole treatment (HR 2.55; 95 % CI 1.22-5.33; p = 0.01) were associated with failure. CONCLUSIONS: Laboratory values at presentation can predict which patients with hyperthyroidism are at risk for failing RAI treatment. Higher doses of RAI or surgical referral may prevent the need for repeat RAI in selected patients.

The role of intraoperative frozen section if suspicious for papillary thyroid cancer.

BACKGROUND: Optimal surgical intervention is straightforward when a fine-needle aspiration (FNA) is diagnostic for papillary thyroid cancer (PTC). However, if there are characteristics of an aspirate suspicious for PTC but not meeting criteria for diagnosis of PTC, the management is less clear. METHODS: Of the 1,051 patients who underwent thyroid surgery at the University of Wisconsin between May 24, 1994, and October 21, 2004, 102 had preoperative FNA cytology that was diagnostic or suspicious for PTC. Within the subgroups of diagnostic for PTC and suspicious for PTC, we evaluated the accuracy of FNA, the utility of frozen section (FS), and the predictive value of demographic and pathologic variables. RESULTS: When diagnostic for PTC, FNA was 97% accurate and FS did not alter management. However, if an FNA was interpreted as suspicious for PTC, there was a 57% (17/30) likelihood of PTC on permanent histology. In this subgroup, FS led to the optimal operative procedure in 96% (25/26) of cases. With the exception of size greater than 4 cm, demographic and pathologic variables did not predict malignancy or increase the likelihood of an FNA being diagnostic for PTC. CONCLUSION: Intraoperative FS is a useful diagnostic tool when an FNA is suspicious for PTC.

Higher serum thyroid stimulating hormone level in thyroid nodule patients is associated with greater risks of differentiated thyroid cancer and advanced tumor stage.

CONTEXT: TSH is a known thyroid growth factor, but the pathogenic role of TSH in thyroid oncogenesis is unclear. OBJECTIVE: The aim was to examine the relationship between preoperative TSH and differentiated thyroid cancer (DTC). DESIGN: The design was a retrospective cohort. SETTING, PARTICIPANTS: Between May 1994 and January 2007, 1198 patients underwent thyroid surgery at a single hospital. Data from the 843 patients with preoperative serum TSH concentration were recorded. MAIN OUTCOME MEASURES: Serum TSH concentration was measured with a sensitive assay. Diagnoses of DTC vs. benign thyroid disease were based on surgical pathology reports. RESULTS: Twenty-nine percent of patients (241 of 843) had DTC on final pathology. On both univariate and multivariable analyses, risk of malignancy correlated with higher TSH level (P=0.007). The likelihood of malignancy was 16% (nine of 55) when TSH was less than 0.06 mIU/liter vs. 52% (15 of 29) when 5.00 mIU/liter or greater (P=0.001). When TSH was between 0.40 and 1.39 mIU/liter, the likelihood of malignancy was 25% (85 of 347) vs. 35% (109 of 308) when TSH was between 1.40 and 4.99 mIU/liter (P=0.002). The mean TSH was 4.9+/-1.5 mIU/liter in patients with stage III/IV disease vs. 2.1+/-0.2 mIU/liter in patients with stage I/II disease (P=0.002). CONCLUSIONS: The likelihood of thyroid cancer increases with higher serum TSH concentration. Even within normal TSH ranges, a TSH level above the population mean is associated with significantly greater likelihood of thyroid cancer than a TSH below the mean. Shown for the first time, higher TSH level is associated with advanced stage DTC.