[Incidence of immunogenic hyperthyroidism after radioiodine therapy of focal thyroid gland autonomy. Results of a multicenter study].
BACKGROUND
There are case reports in the literature that patients occasionally develop immunogenic hyperthyroidism 2 to 14 months following iodine-131-therapy of focal, non-immunogenic, autonomous thyroid nodules with a prevalence between 0.05 and 2.5%. Purpose of this multicenter evaluation was to assess the appearance of this phenomenon in a larger patient population.


METHODS
So far 2867 patients out of 4 university hospitals are included in our study focusing on the appearance of pathologically elevated levels of thyrotropin-receptor-antibodies (TRAb) combined with hyperthyroidism following iodine-therapy. Records of the patients were screened for pre- and post-therapeutic biochemical tests, scintigraphic uptake patterns and ultrasound findings of the thyroid.


RESULTS
Nineteen of 2867 patients with pretherapeutically scintigraphic "hot nodules" developed recurrent hyperthyroidism suggestive for immunogenic genesis 2 to 12 months following iodine-131-therapy (elevated TRAb-levels, homogeneous uptake in Tc-99m-pertechnetate scans). Pretherapeutically, 9 of these patients presented with a strictly focal scintigraphic uptake-pattern, 10 cases with a mixed disseminated-focal pattern. Because of missing pretherapeutic TRAb-tests in 8/9 patients presenting with a strictly focal scintigraphic uptake pattern, postradiogenic immunogenic hyperthyroidism could be reliably assessed in 1 case only.


CONCLUSIONS
One could speculate that iodine-131-therapy may stimulate immunogenic mechanisms finally leading to immunogenic hyperthyroidism. Posttherapeutically observed hyperthyroidism following iodine-treatment might be based on an exacerbation of a preexisting--clinically not relevant/detectable--immunothyropathia. Also pretherapeutic TRAb-negative immunogenic hyperthyroidism could not be definitely excluded. Our multicenter data collected in a large patient population show similar results to the case reports of immunogenic hyperthyroidism following iodine-131-treatment in smaller populations. Therfore, the occurrence of this phenomenon plays a minor role regarding to its prevalence. Therapeutical consequences in treatment of functional thyroid autonomy are not recommended.
Klinik und Poliklinik für Nuklearmedizin, Ludwig-Maximilians-Universität München.
M
M
Weiss
R
R
Görges
C
C
Hirsch
J
J
Bader
K
K
Tatsch
K
K
Hahn
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D006980:Hyperthyroidism / Q000453:epidemiology / Q000209:etiology*; D007457:Iodine Radioisotopes / Q000009:adverse effects* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D011832:Radiation Injuries / Q000453:epidemiology / Q000209:etiology*; D012189:Retrospective Studies; D013961:Thyroid Gland / Q000528:radiation effects*; D016606:Thyroid Nodule / Q000532:radiotherapy*; D013967:Thyroiditis, Autoimmune / Q000453:epidemiology / Q000209:etiology*
D007457:Iodine Radioisotopes
Auftreten einer immunogene Hyperthyreose nach Radioiod-Therapie fokaler Schilddrüsenautonomien. Ergebnisse einer multizentrischen Erhebung.