Morphological and functional changes in neonatally X-irradiated thyroid gland in rats

Exposure to ionized radiation in childhood has been recognized as a risk factor for the development of thyroid cancer and possibly for other thyroid disorders. However, the effects of neonatal radiation exposure on thyroid morphology and functions have never been explored despite its potential importance. One-week-old male Wistar rats were subjected to cervical X-irradiation at 6 and 12 Gy. Animals were examined at the ages of 2, 8 and 18 weeks old. For comparison, 8-week-old rats were cervically X-irradiated at the same doses. Thyroid histology was examined by computer-assisted microscopy to measure areas of colloid and epithelium of thyroid follicles as well as epithelial heights. In rats that received cervical X-irradiation at 1 week old, the colloid size of thyroid follicles decreased at the age of 8 weeks old in a radiation-dose dependent manner. This morphological change was persistently found at 18 weeks old. There were no significant differences in serum total T3 or T4 levels among the groups. Serum TSH levels increased significantly in 8-week-old rats neonatally X-irradiated. Thyroglobulin (Tg) mRNA and protein expressions were significantly decreased in the neonatally-irradiated group while thyroid peroxidase mRNA express increased at 18 weeks old. None of these changes were observed in the rats X-irradiated at 8 weeks old. In conclusion, our results clearly demonstrated that neonatal rat thyroid was sensitive to ionized radiation, developing specific morphological changes characterized by smaller thyroid follicles along with changes in serum TSH levels and Tg expressions in the thyroid tissue.

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

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.

[The structural-functional status of the thyroid in patients with nodular goiter evacuated from the 30-kilometer zone of the Chernobyl Atomic Electric Power Station]

An analysis was performed of results of ultrasonic and hormonal investigations in 239 patients with nodular goiter revealed in a screening-type clinical and laboratory examination of the 3371 persons evacuated from the 30-km zone of ChNPP, at their ages randing between 18 to 68 years. In 84.20% of patients in the group who took part in the elimination of effects of the Chernobyl accident (PEEA)--"PEEA + the evacuated"--the diameter of the nodules did not exceed 1 cm, in 6.1% it ranged from 1 to 2 cm, and in 13.41% it exceeded 2 cm. Distribution of nodules in the group "the evacuated" did not differ much from that in the above group. In 20% of patients with nodular goiter, there were functional disturbances concurrent with the autoimmune processes. No effects were detected of small doses of extra irradiation on the pattern of structural-and-functional indices in patients with nodular goiter evacuated from the 30-km zone of ChNPP who took part in EEA.

Development of primary hypothyroidism with antithyroglobulin, antiperoxidase, and blocking-type thyrotropin receptor antibodies after radiation therapy for neuroblastoma

We describe a girl with hypothyroidism and blocking-type thyrotropin receptor antibodies that developed after chemotherapy and irradiation of the neck region for neuroblastoma. Results of thyroid studies before treatment were normal. Twenty months after completion of treatment, the girl had hypothyroidism with high titers of blocking-type thyrotropin receptor antibodies, antithyroglobulin, and antiperoxidase antibodies.

[The effect of environmental factors on the concentration of tumor markers in the blood serum and on the indices characterizing thyroid function]

Combined versus separate exposure of male organism to cesium-137 and chemical agents results in a more pronounced hyperferritinemia in the former case. In female chemists the ferritin level is dependent to a considerable extent on the menstrual cycle showing a tendency for the iron-containing protein level to decrease because of the action of a number of chemical agents. The rise of the level of cancer embryonic antigen is more readily seen in persons with high levels of cesium-137. Concentrations of carbohydrate antigen (CA-125) and mucin-like antigen are appreciably higher in female chemists incorporating cesium-137, and in those within the 30-km radius of the ChNPP. The level of thyroglobulin was raised in the chemists having a background incorporation of cesium, the liquidators of the aftermaths, and particularly in those happened to be in the 30-km zone. Each of the unfavourable factors taken separately (chemical agent or cesium-137) had lesser effect on the degree of elevation of TG content and hormone-forming function of the thyroid gland. An additional information has been obtained concerning the risk groups, which, however, serves as an indirect measure of carcinogenic effect various environmental factors exert on the organism.