Autoimmune thyroiditis and exposure to iodine 131 in the Ukrainian cohort study of thyroid cancer and other thyroid diseases after the Chornobyl accident: results from the first screening cycle (1998-2000).
BACKGROUND
Due to the Chornobyl accident, millions were exposed to radioactive isotopes of iodine and some received appreciable iodine 131 (131I) doses. A subsequent increase in thyroid cancer has been largely attributed to this exposure, but evidence concerning autoimmune thyroiditis (AIT) remains inconclusive.


OBJECTIVE
The objective of the study was to quantify risk of AIT after 131I exposure.


METHODS
Baseline data were collected from the first screening cycle (1998-2000) of a large cohort of radiation-exposed individuals (n = 12,240), residents of contaminated, iodine-deficient territories of Ukraine. Study individuals were under the age of 18 yr on April 26, 1986, and had thyroid radioactivity measurements made shortly after the accident.


RESULTS
AIT was defined a priori based on various combinations of elevated antibodies to thyroid peroxidase (ATPO), TSH, and clinical findings; elevated ATPO were considered to be an indicator of thyroid autoimmunity.


RESULTS
No significant association was found between 131I thyroid dose estimates and AIT, but prevalence of elevated ATPO demonstrated a modest, significant association with 131I that was well described by several concave models. This relationship was apparent in individuals with moderately elevated ATPO and euthyroid, thyroid disease-free individuals.


CONCLUSIONS
Twelve to 14 yr after the Chornobyl accident, no radiation-related increase in prevalence of AIT was found in a large cohort study, the first in which 131I thyroid doses were estimated using individual radioactivity measurements. However, a dose-response relationship with ATPO prevalence raises the possibility that clinically important changes may occur over time. Thus, further follow-up and analysis of prospective data in this cohort are necessary.
Tronko
M D
MD
Institute of Endocrinology and Metabolism, 04114 Kyiv, Ukraine.
Brenner
A V
AV
Olijnyk
V A
VA
Robbins
J
J
Epstein
O V
OV
McConnell
R J
RJ
Bogdanova
T I
TI
Fink
D J
DJ
Likhtarev
I A
IA
Lubin
J H
JH
Markov
V V
VV
Bouville
A C
AC
Terekhova
G M
GM
Zablotska
L B
LB
Shpak
V M
VM
Brill
A B
AB
Tereshchenko
V P
VP
Masnyk
I J
IJ
Ron
E
E
Hatch
M
M
Howe
G R
GR
D000293:Adolescent; D001323:Autoantibodies / Q000097:blood; D001324:Autoantigens / Q000276:immunology; D002277:Carcinoma / Q000453:epidemiology*; D047852:Chernobyl Nuclear Accident; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007453:Iodide Peroxidase / Q000276:immunology; D007457:Iodine Radioisotopes / Q000009:adverse effects*; D033862:Iron-Binding Proteins / Q000276:immunology; D008297:Male; D008403:Mass Screening / Q000379:methods; D009381:Neoplasms, Radiation-Induced / Q000453:epidemiology*; D011829:Radiation Dosage; D013959:Thyroid Diseases / Q000453:epidemiology*; D013964:Thyroid Neoplasms / Q000453:epidemiology*; D013967:Thyroiditis, Autoimmune / Q000453:epidemiology*; D014455:Ukraine / Q000453:epidemiology
D001323:Autoantibodies; D001324:Autoantigens; D007457:Iodine Radioisotopes; D033862:Iron-Binding Proteins; C056658:TPO protein, human; D007453:Iodide Peroxidase