Determination of the Kinetic Parameters for 123I Uptake by the Thyroid, Thyroid Weights, and Thyroid Volumes in Present-day Healthy Japanese Volunteers

Abstract

The purpose of this study was to evaluate the kinetic parameters that determine the uptake rate of radioiodide in the thyroid over 24 h after administration and to estimate thyroid volumes/masses of present-day Japanese. Methods: We determined the thyroid uptake rate of 123I in healthy male Japanese after oral administration (4.5–8.0 MBq) without iodine restriction. Masses of thyroid glands were collected in 2012–2016 during autopsies of 7,651 male and 3,331 female subjects. Volumes of thyroid glands were estimated by ultrasonography and magnetic resonance imaging in 52 male subjects. Results: The thyroid uptake rate of 123I for 24 h was 16.1 ± 5.4%. Kinetic model analysis was conducted to obtain the clearances (L h−1) for thyroid uptake and urinary excretion of 123I (0.499 ± 0.258 and 2.10 ± 0.39 L h−1, respectively). The masses of thyroid glands were on average 19.8 g (95% confidence interval of 18.3−19.5 g) and 15.5 g (95% confidence interval of 14.7−16.2 g) in male and female subjects aged 19–52 y, respectively. Volumes of thyroid glands estimated by ultrasonography and magnetic resonance imaging were 17.5 ± 5.2 and 14.2 ± 5.3 mL, respectively. In healthy Japanese, there has been no significant change for at least 50 y in the thyroid uptake of radioiodide over 24 h or in its kinetic parameters. These Japanese-specific kinetic parameters will allow quantitative estimation of the radiation exposure from the Fukushima accident and its variance during the individual’s evacuation from or stay in Fukushima.

Reconstruction of residents’ thyroid equivalent doses from internal radionuclides after the Fukushima Daiichi nuclear power station accident

“…www.nature.com/scientificreports www.nature.com/scientificreports/ WSPEEDI_2019DB, which was improved by referring to hourly measured 137 Cs concentrations in air at multiple SPM stations 26 . In addition, two factors that influence TEDs were incorporated into the present dose estimation: a decontamination factor for sheltering and a correction factor for dose coefficient to reflect the lower thyroid iodine uptake rate in Japanese 18,24 . By these procedures, we estimated 131 I-TEDs as realistically as possible.…”

“…However, such individual information was not available or was obtained only in exceptional cases. Instead of assessing individual dietary habits, we adopted the distribution of iodine uptake rate reported by Kudo, who experimentally assessed the rate among normal subjects without iodine restriction 18 . Sixth, SF, a correction factor for short-lived radionuclides, might vary from place to place on 12 March, as P1 was a mixture of two plumes released by venting at 14:30 and by a hydrogen explosion at 15:36, and venting might deplete low volatile 132 Te in the plume.…”

“…As reported 13 , WSPEEDI-2019DB has simulated the 131 I concentrations of 131 I-particulate, 131 I-elementalal vapor, and 131 I-methylated forms separately with the source term of 131 I assuming 50%-particulate, 20%-elemental, and 30%-methyl forms. FC is a correction factor for the dose coefficient because iodine uptake rate is 18.5% (SD 6.0%), lower than the 30% in the ICRP thyroid model, while thyroid volume in Japanese does not differ from that of ICRP reference man 18 . DF shelter is a decontamination factor to reflect sheltering.…”

Estimation of the Thyroid Equivalent Doses to Residents in Areas Affected by the 2011 Fukushima Nuclear Disaster Due to Inhalation of 131I Based on Their Behavioral Data and the Latest Atmospheric Transport and Dispersion Model Simulation

“…Several studies of the public's exposure in the FDNPP accident have addressed the relatively low thyroid iodine uptake (TIU) (Hosoda et al 2013;Kim et al 2016c;Ohba et al 2020). It was also reported that the average TIU factors in Japanese subjects were mostly in the range of 0.15-0.20 (Yoshizawa and Kusama 1976), which was also found to be true in a very recent study (Kudo et al 2020). The relatively low TIU in the Japanese is due to their diet (in which stable iodine is abundant) and will reduce the TED coefficients that were calculated assuming the TIU factor of 0.3; the corresponding coefficients for the Japanese are thought to be decreased by the ratio of the Japanese TIU factor to 0.3.…”

Communicating with residents about 10 years of scientific progress in understanding thyroid cancer risk in children after the Fukushima Dai-ichi Nuclear Power Station accident

“…Once Kudo et al . [ 39 ] demonstrated the distribution of thyroid weight, iodine uptake rate and other bio-kinetic parameters in Japanese people, it became possible to propose a correction factor for the 131 I-dose coefficient. Seventh, in contrast to UNSCEAR’s supposition that Fukushima residents consumed contaminated vegetables and other foodstuffs grown in Fukushima Prefecture, Hirakawa et al .…”