The predominant form of non-toxic goiter in Greece is now autoimmune thyroiditis

Abstract

Endemic non-toxic goiter (NTG) in Greece has been attributed primarily to iodine deficiency. Thirty years ago about 60% of the prepubertal boys and girls examined in endemic goiter regions presented with NTG and among them thyroid autoimmunity was rarely detected. Although iodine supplementation has corrected this deficiency during the past 30 years, new cases of NTG still appear. To evaluate the prevalence and type of NTG and the effect of iodine supplementation on them in Greece at present, we performed two cross-sectional clinical studies and a retrospective pathology one: (i) thyroid gland volume and urinary iodine excretion (UIE) were assessed in a representative sample of 1213 schoolchildren from previously endemic and non-endemic regions; (ii) serum thyroxine, tri-iodothyronine, TSH, thyroid autoantibodies (AAB) (anti-thyroid peroxidase and anti-thyroglobulin antibodies) and UIE (in 60 patients) were measured in 300 consecutive patients with NTG from Athens and Heraklion; and (iii) we compared the prevalence of autoimmunity among fine needle aspiration smears of benign thyroid pathologies performed by the same pathologist between 1985 and 1986 (975 cases) and between 1994 and 1995 (2702 cases). We found that 12.5% of the schoolchildren examined in regions with a previous history of endemic goiter had NTG, whereas this percentage was only 1.7% in areas without such a history. In Athens (61.6%) and Heraklion (58.5%) a substantial number of NTG patients were AAB positive and biochemically hypothyroid. UIE in Athens did not differ between patients with autoimmune goiter (ATG) and simple goiter. The prevalence of autoimmune stigmata in pathology smears has increased from 5.94% (years 1985-1986) to 13.91% (years 1994-1995) (P < 0.05). We conclude that: (i) the persistence of endemic goiter in regional foci despite iodine deficiency correction suggests a possible role for a naturally occurring goitrogen; (ii) ATG is the predominant form of NTG in Greece nowadays; and (iii) the five-fold decrease in the prevalence of NTG during the past 30 years followed by the increase of ATG may support the relative character of the latter.

Fine-needle aspiration biopsy of the thyroid in an area of endemic goitre: influence of restored sufficient iodine supplementation on the clinical significance of cytological results

“…An analysis of the results of antithyroid antibody assays should be performed to formulate conclusions with regards to the changes in the occurrence of chronic thyroiditis. However, similar observations were reported in a study from Greece by Doufas et al (35) and from Argentina by Harach & Williams (28) (although during much longer intervals before and after introduction of iodine prophylaxis). Autoimmune thyroid diseases are more common in iodine-sufficient areas than in areas with low iodine intake (31,36), but the true incidence of Hashimoto thyroiditis has not yet been clearly demonstrated with the aid of epidemiological methods (29).…”

Prevalence of Anti-Thyroid Antibodies in Patients with Primary Thyroid Disorders

“…It has been reported that thyroid autoimmunity is rare in iodine deficient areas but becomes more prevalent with improvement in iodine nutrition (6)(7)(8). Locally, it is a requirement that all domestic salt is iodinated in an attempt to reduce the occurrence of iodine deficiency disorders (9).…”

Autonomously functioning thyroid nodules in a former iodine-deficient area commonly harbor gain-of-function mutations in the thyrotropin signaling pathway

“…Iodine deficiency was endemic in post-Second World War Greece, but has been corrected over the last 20 years by increased use of iodized salt and improved socioeconomic conditions (21). As a result, the prevalence of goiter has substantially decreased (22). However, iodine deficiency still persists in some mountainous regions, including areas of Southwestern Greece (23).…”