Frühveränderungen der Schilddrüsenhormone nach Radiojodtherapie der Hyperthyreose unter Berücksichtigung von Ätiologie und begleitender Medikation

Summary Aim: In spite of extensive use of 131I for treatment of hyperthyroidism, the results of early outcome are variable. In our prospective clinical study we tested whether 131I induced necrosis causing clinical aggravation of hyperthyroidism and increasing the free thyroid hormone concentration in the serum of patients with solitary toxic adenoma not pretreated with antithyroid drugs. Patients and methods: 30 consecutive patients were treated with 925 MBq 131I. Serum concentration of thyrotropin (TSH), free thyroxine (fT4), free triiodothyronine (fT3), thyroglobulin (Tg), and interleukin-6 (IL-6) were measured before and after application of 131I. Results: After application of 131I no clinical worsening was observed. FT4 and fT3 concentration did not change significantly within the first five days, whereas both of them significantly decreased after 12 days (p <0.0001). Slight and clinically irrelevant increase in the level of the two thyroid hormones was observed in 9 patients. Furthermore, we observed a prolonged increase in Tg concentration and a transient increase in IL-6 concentration. Conclusion: Neither evidence of any clinical aggravation of hyperthyroidism nor any significant increase in thyroid hormone concentration by 131I induced necrosis of thyroid cells was found. Therefore, the application of 131I may be considered as a safe and effective treatment for patients with hyperthyroidism due to toxic adenoma.

Section: Discussionsupporting

confidence: 94%

“…change of thyroid hormone concentration in serum after 131 I application are contradictory. 131 I has been shown either to increase (7,21), decrease (1,6,14,26), or cause no consistent short-term change of thyroid hormone levels (20,23).…”

Section: Nuklearmedizin 2002; 41: 178-83mentioning

confidence: 99%

Early change of thyroid hormone concentration after 131I treatment in patients with solitary toxic adenoma

Pirnat

Fidler²,

Zaletel³

et al. 2002

“…Exacerbation of hyperthyroidismdue to increased thyroid hormone concentrations afterr adioiodinet herapy is controversially discussed. In an overviewMcDermott et al reporteda ni ncidenceo fs everee xacerbation of 0.88% in 2975 patients (24).Aggravation of thyreotoxicosis wasreported as consequenceofthe release of storedthyroid hormonesf ollowing acute radiation damage.Inaccordancewith this,some groups observedthatserum concentrationsofthyroid hormonesw eree levateda fterr adioiodine treatment (11, 18,3 2), buto thers foundnochanges (19,34). Pirnat et alreported that application of 131 Ialonedoesnot result in exacerbation of hyperthyroidism.…”

Section: Clinical Consequencesmentioning

confidence: 75%

Reduced radioiodine uptake at increased iodine intake and 131I-induced release of “cold” iodine stored in the thyroid

Haase¹,

Seyfarth²,

Wenzel³

et al. 2005

Summary Aim: The extent of urinary iodine excretion (UIE) provides information about iodine supply and release. In the present study we investigated correlations between UIE and radioiodine uptake (RIU) as well as effects of radioiodine therapy on UIE in patients with autonomous goitre. Patients, methods: In 197 consecutive patients with thyroid autonomy, UIE was measured twice during radioiodine test (RITe) and correlated with RIU. In 98 of these patients, thyroglobulin and thyroid volume (V) were determined prior to therapy. Individual changes in urinary iodine excretion (ΔUIE) and TG (ΔTG) could be investigated four weeks (4W) and six months (6M) after radioiodine therapy. Additionally, ΔV was determined 6M after therapy. ΔUIE, ΔTG and ΔV were correlated with target dose and target volume. Results: Patients with higher iodine excretion exhibited significantly lower thyroidal radioiodine uptake values. Twofold increased UIE prior to therapy decreased radioiodine uptake by 25%. Compared with pretherapeutic values, UIE and TG were significantly increased four weeks after radioiodine therapy (p <0.001). Median values of both parameters were found to be doubled. The product of target dose and target volume was not only correlated with a decrease of thyroid volume 6M after therapy, but also with an increase of UIE and TG in the early phase after therapy. Conclusions: It was confirmed that UIE during RITe is a measure for iodine intake and can be used to investigate the competition between stable iodine and radioiodine. The increase of UIE and TG four weeks after therapeutic administration of radioiodine can be explained by disintegrated thyroid follicles. The therapy-induced iodine release may be one important cause for the development of hyperthyroidism in some patients during the first weeks after radioiodine therapy. It may contribute to the known decrease of radioiodine uptake after preapplications of 131I in various thyroid diseases.

“…This observation is in accordance with Andrade et al 1and Burch et al (4) who found significant decrease of both thyroid hormones five days after 131 I in 28 and 21 Graves' patients not pretreated with MMI. Similarly, Kreisig et al (14) reported significant decrease of total T 3 in 396 unselected hyperthyroid patients pretreated or not pretreated with MMI. Other authors (20,26) detected no short-term change of thyroid hormone levels.…”

Section: Nuklearmedizin 4/2004mentioning

confidence: 86%

“…Considering the acute thyroid hormone changes after 131 I application, the results are contradictory. Some authors found short-term increase of thyroid hormone concentrations (7,21), whereas others observed no changes (20,26) or even immediate decrease of thyroid hormone concentrations (1,4,5,14). To prevent possible exacerbation of hyperthyroidism antithyroid drugs are frequently prescribed before 131 I treatment (9,16,22).…”

Section: Discussionmentioning

confidence: 99%

Early changes of thyroid hormone concentrations after 131I therapy in Graves’ patients pretreated or not with methimazole

Zaletel¹,

Gaberšček²,

Fidler³

et al. 2004

SummaryAim: Despite extensive use of 131I therapy for Graves’ hyperthyroidism the treatment regimen with 131I and antithyroid drugs remain under discussion. In our prospective clinical study we followed acute thyroid hormone changes after 131I in patients not pretreated with methimazole (MMI) and in patients with different MMI pretreatment regimens. Patients, methods: 187 patients were treated with fixed activity of 550 or 740 MBq of 131I. First group (71 patients) received 131I alone. In the second group (57 patients) MMI was stopped seven days before 131I. The third group (59 patients) received MMI until 131I application. Initial free triiodothyronin and free thyroxin were measured in the second group 7 and 2 days before 131I therapy and in all three groups on the day of 131I application as well as 2, 5, 12, and 30 days afterwards. Absorbed dose was measured in each patient. Results: In the non-pretreated group 131I application was followed by a significant decrease of fT4 in 5 days and of fT3 in 2 days, higher reduction was detected in patients with higher baseline values. In MMI pretreated patients significant but clinically irrelevant increase of both thyroid hormones was detected with maximum value 7 days after discontinuation in the second group and 5 days after discontinuation in the third group. Additionally, in patients of the third group absorbed dose of 131I was significantly lower relative to other two groups. We found no correlation between absorbed dose of 131I and thyroid hormone changes. Conclusion: Our study demonstrates that 131I application alone does not result in exacerbation of hyperthyroidism and therefore it may be considered as safe. Additionally, MMI withdrawal causes significant but clinically irrelevant elevation of thyroid hormones.