Thyroid ultrasonography as a tool for detecting thyroid autoimmune diseases and predicting thyroid dysfunction in apparently healthy subjects

In order to establish its usefulness for the diagnosis and follow-up of thy roid autoimmune diseases, thyroid ultrasonography together with free T-4 (F T4), free T-3 (FT3), TSH, antibodies (Tg Ab) and thyroperoxidase antibodies (TPO Ab) were performed and re-evaluated during a 3-yr follow-up in 482 ap parently healthy subjects, living in a borderline iodine-sufficient urban a rea. Thyroid dysfunction was found in 7 out of 12 (58.3%) subjects with cir culating thyroid autoantibodies, who also had thyroid hypoechogenicity (2 h ad overt and 3 subclinical hypothyroidism at booking; 2 developed subclinic al hypothyroidism during the follow-up), and in none of the 12 subjects wit h normal thyroid echostructure (chi (2)=7.26, p=0.007). Thyroid dysfunction was found in 4 out of 29 (13.7%) subjects with negative Tg and/or TPO Ab w ho also had thyroid hypoechogenicity (1 had Graves' disease at booking, 1 d eveloped Graves' disease and 2 subclinical hypothyroidism during the follow -up), and in none of the 429 with normal thyroid echostructure (chi (2)=82. 03, p <0.0001). Although positive TPO and/or Tg Ab were more frequent (24/4 82, 5%) in subjects with thyroid dysfunction (7/11) than in those who remai ned euthyroid during the study (17/471, chi (2)=69.66, p <0.0001), thyroid hypoechogenicity had a higher sensitivity than the positivity of thyroid au toantibody tests (100 vs 63.3%) for diagnosing or predicting thyroid dysfun ction. In conclusion: 1) thyroid ultrasonography is a useful tool to detect thyroid autoimmune disease in apparently healthy subjects; 2) present and future thyroid dysfunction is more readily predicted by a hypoechogenic pat tern at thyroid ultrasound than by the occurrence of serum thyroid autoanti bodies. (C) 2001, Editrice Kurtis.