The relationship among iodine intake, goiter prevalence, and thyroid autoimmunity remains controversial. In the present article, we report the prevalence of antithyroid antibodies (ATA) in relation to iodine intake, frequency of goiter, and thyroid function in a large group of Sardinian schoolchildren living in areas with borderline iodine sufficiency, or mild to moderate iodine deficiency. A total of 8,040 schoolchildren (4,194 males, 3,846 females, ages 6-15 years) from 29 communities were examined between 1986-1994. Thyroid size was assessed by palpation, according to the Pan American Health Organization (PAHO) criteria. In all cases antimicrosomal (MAb) or antithyroid peroxidase antibodies (TPOAb) and thyrotropin (TSH) were assayed. Urinary iodine was determined in a subgroup of 820 children. ATA was detected in 235 (2.92%) sera (88 males, 2.12%; 147 females, 3.82%; chi2 = 20.41, p < 0.0001). ATA prevalence ranged between 0.0%-7.3% in the 29 communities without any geographical correlation with goiter prevalence and urinary iodine excretion. However, ATA was more frequently detected in goitrous children, especially in females. The presence of ATA was not age-dependent in males, whereas a significant increase of ATA was observed in females older than 11 years of age. Seventy-seven (0.96%) children showed borderline to slightly increased serum TSH (>5.2-32 mU/L). Increased serum TSH concentration was more frequently found in children with ATA, especially at higher titers. In summary, our study in Sardinian schoolchildren indicates: (1) ATA display geographical heterogeneity, which seems to be unrelated to goiter prevalence and/or to iodine supply; (2) ATA are more frequently detected in females older than 11 years of age, suggesting that puberty has a role in determining the predominance in females of thyroid autoimmunity; (3) although most goitrous children are ATA-negative, the prevalence of ATA is increased in children with enlarged glands; (4) ATA is associated with an increased prevalence of subclinical hypothyroidism.

TPOAb prevalence in adolescents exposed to radioactive fallout was still increased in Belarus 13-15 yr after the Chernobyl accident. This increase was less evident than previously reported and was not accompanied by thyroid dysfunction. Our data suggest that radioactive fallout elicited a transient autoimmune reaction, without triggering full-blown thyroid autoimmune disease. Longer observation periods are needed to exclude later effects.

The objective of this paper was to study prospectively the course of clinically relevant thyroid dysfunction in a cohort of patients on long-term lithium treatment. Patients (N = 150) who had undergone a cross-sectional evaluation of their thyroid function in 1989, when they were at different stages of lithium treatment, were followed up for the presence of thyroid autoimmunity, hypothyroidism, and goiter during a further period of lithium exposure of up to ten years. The following annual rates of newly developed thyroid dysfunction were observed: autoimmunnity (1.4%), subclinical hypothyroidism (1.7%), and goiter (2.1%). Subjects with thyroid autoimmunity had a higher chance of requiring substitution treatment with levothyroxine for subclinical hypothyroidism compared with subjects with no evidence of thyroid autoimmunity (13/32 = 41% versus 7/118 = 6%). Subjects (N = 15) who were prescribed carbamazepine in addition to lithium showed a significant decrease of TSH concentrations. In patients already being treated with lithium for several years, the overall incidence of hypothyroidism, goiter, and thyroid autoimmunity were comparable with those reported for the general population. However, lithium exposure may represent an additional risk factor for hypothyroidism in women and/or in the presence of thyroid autoimmunity.

An elevated prevalence of clinical and subclinical autoimmune thyroid autoimmunity was found in Sardinian celiac patients, especially in those displaying the DQB1*0502 genotype; this finding could be related to a particular genetic background of the Sardinian population.

This is the first study reporting the prevalence of Type 1 diabetes autoantibodies in a selected cohort of genetically homogeneous children and adolescents with autoimmune thyroiditis. The main finding was that the prevalence of Type 1 diabetes autoantibodies and of newly diagnosed Type 1 diabetes in patients with autoimmune thyroiditis was significantly higher than that observed in the general paediatric population, suggesting that children with autoimmune thyroiditis are at increased risk of developing Type 1 diabetes.