Thyroid dysfunction and autoimmune thyroid diseases among atomic-bomb survivors exposed in childhood.

Thyroid dysfunction and autoimmune thyroid diseases among atomic-bomb survivors exposed in childhood.

J Clin Endocrinol Metab. 2017 May 01;:

Authors: Imaizumi M, Ohishi W, Nakashima E, Sera N, Neriishi K, Yamada M, Tatsukawa Y, Takahashi I, Fujiwara S, Sugino K, Ando T, Usa T, Kawakami A, Akahoshi M, Hida A

Abstract
Context: The risk of thyroid cancer increases and persists for decades among individuals exposed to ionizing radiation in childhood, while long-term effects of childhood exposure to medium to low doses radiation on thyroid dysfunction and autoimmune thyroid diseases have remained unclear.
Objective: To evaluate radiation-dose responses for the prevalence of thyroid dysfunction and autoimmune thyroid disease among atomic -bomb survivors exposed in childhood.
Design, Setting, and Participants: Hiroshima and Nagasaki atomic-bomb survivors who were younger than 10 years old at exposure underwent thyroid examinations at the Radiation Effects Research Foundation between 2007 and 2011, which was 62-66 years after the bombing. Data from 2,668 participants (mean age, 68.2 years; 1,455 women) with known atomic-bomb thyroid radiation doses (mean dose, 0.182 Gy; dose range, 0-4.040 Gy) were analyzed.
Main Outcome and Measures: Dose-response relationships between atomic-bomb radiation dose and the prevalence of hypothyroidism, hyperthyroidism (Graves' disease), and positive for antithyroid antibodies.
Results: Prevalences were determined for hypothyroidism (129 cases, 7.8%), hyperthyroidism (32 cases of Graves' disease, 1.2%), and positive for antithyroid antibodies (573 cases, 21.5%). None of these was associated with thyroid radiation dose. Neither thyroid antibodies-positive nor -negative hypothyroidism was associated with thyroid radiation dose. Additional analyses using alternative definitions of hypo- and hyperthyroidism found that radiation dose responses were not significant.
Conclusions: Radiation effects on thyroid dysfunction and autoimmune thyroid diseases were not observed among atomic-bomb survivors exposed in childhood, at 62-66 years earlier. The cross-sectional design and survival bias were limitations of this study.

PMID: 28472357 [PubMed - as supplied by publisher]

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