Thyroid nodules, thyroid function and dietary iodine in the Marshall islands.
BACKGROUND
Thyroid nodules have been found to be common in the population of the Marshall Islands. This has been attributed to potential exposure of radioiodines from the nuclear weapons tests on Bikini and Eniwetok between 1946 and 1958.


METHODS
In order to get a full picture of thyroid pathology in the Marshallese population potentially exposed to radioactive fallout we performed a large thyroid screening programme using palpation, high resolution ultrasound and fine needle biopsies of palpable nodules. In addition, various parameters of thyroid function (free T3, free T4, thyroid stimulating hormone [TSH]) and anti-thyroid antibodies were examined in large proportions of the total population at risk. Since dietary iodine deficiency is an established risk factor for thyroid nodules, iodine concentration in urine samples of 362 adults and 119 children was measured as well as the iodine content of selected staple food products.


RESULTS
The expected high prevalence of thyroid nodules was confirmed. There was no indication of an increased rate of impaired thyroid function in the Marshallese population. A moderate degree of iodine deficiency was found which may be responsible for some of the increased prevalence of thyroid nodules in the Marshallese population.


CONCLUSIONS
Studies on the relationship between exposure to radioiodines and thyroid nodules need to take dietary iodine deficiency into account in the interpretation of findings.
Takahashi
T
T
Department of Preventive Medicine and Health Promotion, Nagaski University School of Medicine, Japan.
Fujimori
K
K
Simon
S L
SL
Bechtner
G
G
Edwards
R
R
Trott
K R
KR
D000328:Adult; D002648:Child; D004032:Diet; D004781:Environmental Exposure / Q000009:adverse effects; D005260:Female; D006801:Humans; D007455:Iodine / Q000097:blood / Q000172:deficiency* / Q000652:urine; D007457:Iodine Radioisotopes / Q000009:adverse effects; D008297:Male; D008849:Micronesia / Q000453:epidemiology; D008875:Middle Aged; D009381:Neoplasms, Radiation-Induced / Q000453:epidemiology / Q000209:etiology / Q000378:metabolism; D015995:Prevalence; D012189:Retrospective Studies; D011795:Surveys and Questionnaires; D013960:Thyroid Function Tests; D013963:Thyroid Hormones / Q000378:metabolism*; D016606:Thyroid Nodule / Q000453:epidemiology* / Q000209:etiology / Q000378:metabolism
D007457:Iodine Radioisotopes; D013963:Thyroid Hormones; D007455:Iodine