Thyroid structure and size and two-year follow-up of solitary cold thyroidnodules in an unselected population with borderline iodine deficiency

Objective: Multinodular goitre has been found with a high prevalence in iod ine-deficient areas, but less frequently in iodine-replete areas; the iodin e intake sufficient to prevent goitre has not been established, however. Methods: We report data from an ultrasonic investigation of the thyroid gla nds of 2656 randomly selected subjects aged 41 to 71 years in an area with borderline iodine deficiency Results: Median iodine concentration in spot urine samples was 70 mu g/l. M ultinodular thyroid structure was found in 23% of the population, increasin g in women from 20 to 46% with increasing age, and in men from 7 to 23%. So litary, scintigraphically cold, thyroid nodules >10 mm were found in 2.4% o f the population with the same prevalence in the different age and sex grou ps. Two years of follow-up of these cold nodules revealed no signs of malig nancies. Median thyroid volume was 11.0 ml. Thyroid enlargement (> 18 ml fo r women and >25 ml for men) was found among 13.1% of the women and 6.2% of the men, and the prevalence increased with age. The presence of thyroid nod ules was related to positive anti-thyroperoxidase antibody (TPO Ab) litres, whereas thyroid enlargement was associated with iodine excretion <50 mu g/ day. Conclusions: Thyroid enlargement was associated with low iodine excretion a nd median thyroid volume was slightly increased compared with iodine-replet e areas. Multinodular thyroid structure was found with a high prevalence an d was associated with TPO Ab > 200 kU/l. Cold thyroid nodules were moderate ly prevalent, with no cases of detected malignancies during 2 years of foll ow-up.