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.
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.
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.
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.
From the *Dipartimento di Medicina Interna e Specialità Mediche, Unità di Medicina Nucleare and †Dipartimento di Sanità Pubblica e Malattie Infettive, “Sapienza” Università di Roma, Rome, Italy.
Received for publication September 3, 2012; and revision accepted December 29, 2012.
Conflicts of interest and sources of funding: none declared.
Reprints: Giuseppe Ronga, MD, Dipartimento di Medicina Interna e Specialità Mediche, Edificio ex-II Clinica Medica, Viale del Policlinico 155, 00161 Rome, Italy. E-mail: firstname.lastname@example.org.