Thyroid nodules, thyroid function and dietary iodine in the Marshall Islands

Background Thyroid nodules have been found to be common in the population o f the Marshall Islands. This has been attributed to potential exposure of r adioiodines from the nuclear weapons tests on Bikini and Eniwetok between 1 946 and 1958. Methods In order to get a full picture of thyroid pathology in the Marshall ese population potentially exposed to radioactive fallout we performed a la rge thyroid screening programme using palpation, high resolution ultrasound and fine needle biopsies of palpable nodules. In addition, various paramet ers of thyroid function (free T-3, free T-4, thyroid stimulating hormone [T SH]) 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 s elected staple food products. Results The expected high prevalence of thyroid nodules was confirmed. Ther e was no indication of an increased rate of impaired thyroid function in th e Marshallese population. A moderate degree of iodine deficiency was found which may be responsible for some of the increased prevalence of thyroid no dules in the Marshallese population. Conclusion Studies on the relationship between exposure to radioiodines and thyroid nodules need to take dietary iodine deficiency into account in the interpretation of findings.