Autonomous functioning thyroid nodules and 131I in diagnosis and therapy after 50 years of experience: what is still open to debate?

PURPOSE OF THE REPORT: Autonomous functioning thyroid nodules (AFTN), defined as "hot nodules" at thyroid scan, are often cured by radioiodine treatment. The aim of our study was to investigate the long-term outcome in patients treated with an 131I calculated dose, to identify a possible "size-tailored" dose, and to simplify follow-up procedures. PATIENTS AND METHODS: Retrospective analysis was carried out on 1402 cases, covering a period of 50 years, of AFTN treated with an 131I calculated dose. Our study focused on nodular size and mean administered dose. Concordance between thyroid scan and serum TSH levels at 3-6 months from treatment was considered. RESULTS: A single 131I dose was effective for the vast majority of patients (93%). The outcome was influenced by nodular size. On the basis of the Italian dose limit for outpatient treatment, our population was divided into subgroups according to administered doses (more or less than 16 mCi) and nodular dimensions: no differences in outcome were observed for each class of nodule size. A dose ≤10 mCi was effective on the smaller nodules (50.1% of our population). The agreement between TSH and scan after treatment was 90.3% at 3 months and 94.5% at 6 months. CONCLUSIONS: 131I therapy with a calculated dose is an effective treatment of AFTN. If a fixed dose is chosen, 16 mCi is often resolutive and for nodules <3 cm a dose of 10 mCi can suffice. Nodules >5 cm are eligible for surgery. TSH is the only parameter required to evaluate the outcome.

The relationship between 24 h/4 h radioiodine-131 uptake ratio and outcome after radioiodine therapy in 1402 patients with solitary autonomously functioning thyroid nodules.

OBJECTIVE: To evaluate the role of 24 h/4 h uptake ratio (UR) in response to radioiodine-131 ((131)I) therapy in patients with autonomously functioning thyroid nodules (AFTN). METHODS: A total of 1402 consecutive hyperthyroid patients were treated with (131)I, between 1958 and 2005. Therapeutic doses (D) were calculated according to the formula: D = weight of nodule x dose per gram of nodular tissue (q)/24 h (131)I uptake. The ratios of the 24 and 4 h uptake were retrospectively calculated and the patients were grouped according to outcome and q into three groups of UR (< or =1.25; 1.26-1.68; > or =1.69) by means of terziles. RESULTS: Of the 1402 patients, 95 did not respond to (131)I treatment while 93/1307 developed hypothyroidism. Most non-responders (55.8%) had UR < or =1.25, while many hypothyroid patients (66.7%) had UR > or =1.69 (chi (2): P < 0.001). As q increased, the proportion of successfully treated patients increased (level of significance) only in the group with UR < or =1.25; while in the other two terziles, with increasing dose per gram of nodular tissue, the number of successfully treated patients did not increase (level of significance). The cumulative incidence of hypothyroidism was 2.2% at the 1st year after (131)I treatment, increasing to 13.9% at 5 years and 26.2% at 10 years. CONCLUSIONS: The (131)I UR can predict the outcome of (131)I treatment in AFTN and may have utility in modifying treatment in some patients to limit post-radioiodine induced hypothyroidism and treatment failures in order to achieve euthyroidism.

Death from differentiated thyroid carcinoma: retrospective study of a 40-year investigation.

Differentiated thyroid carcinoma (DTC) usually has a good prognosis, but sometimes the course of the disease results in death. The aim of the present study was to assess the effect of some variables in time to death on fatal cases in our series. A total of 83 patients with DTC who died between 1958 and 1998 from differentiated thyroid cancer were retrospectively analyzed with respect to gender, age at diagnosis, histology, percentage of (131)I uptake by postoperative thyroid remnant, site of tumor growth, and its (131)I uptake, metastases and time to death. Univariate analysis revealed a significantly shorter time to death in local recurrence when comparing local lymph node metastases and distant metastases even if neither show (131)I uptake. Multivariate analysis revealed that age at diagnosis was the most important factor in conditioning the time to death. In conclusion, in those patients who died from DTC an older age at diagnosis and presence of local recurrence influenced the time to death independently of (131)I uptake.