title: Functional meaning of scintigraphic and echographic patterns, and of circulating anti-peroxidase antibodies in asymptomatic chronic thyroiditis.
abstract: Asymptomatic chronic thyroiditis (ACT) is a variant of the autoimmune thyroiditis characterized by the presence of circulating anti-thyroid antibodies and the absence of palpable goiter. Thyroid function can be normal but a considerable percentage of ACT patients tend to develop subclinical hypothyroidism over time and thus periodical controls of thyroid hormones and TSH levels are needed. At present, useful parameters for predicting the functional outcome of ACT patients are lacking. To investigate this aspect, we evaluated 57 consecutive ACT patients (51 females, 6 males, aged 22-56 years) by means of thyroid 99mTc-pertechnetate scintigraphy and echography, and by measuring the serum level of anti-peroxidase antibodies (TPOAbs), FT4, T3 and TSH. At first observation, 30 patients were euthyroid whereas 27 had subclinical hypothyroidism. No patient had been previously treated with thyroid hormones. Thyroid scan showed a normal pattern or a diffuse and mild irregular uptake, without differences between euthyroid and subclinical hypothyroid patients. TPOAb levels tend to be higher in patients with subclinical hypothyroidism in comparison to the euthyroid patients (5893 +/- 1423 and 3943 +/- 912 UI/mL, respectively) but the difference was not statistically significant by using Student's "t"-test. Echography showed a normal pattern in 14 patients, while a diffuse hypoechoic pattern in the other cases, mild in 12, moderate in 19 and marked in 12, was found. A significantly higher prevalence of subclinical hypothyroidism was observed in the group of patients with a moderate or marked hypoechoic pattern in comparison to the group with a normo-echoic or mild hypoechoic pattern (70.4% versus 23.0%, Fisher's exact test p = 0.00003). Furthermore, the 3 patients who developed thyroid failure during a one-year follow-up also presented a moderate or marked hypoechoic pattern. Our data suggest that the echo-pattern can be a useful predictor of thyroid failure in ACT patients and thus the echographic evaluation should be included in the diagnostic protocol of these patients.
authors.affiliation: Nuclear Medicine Service, Hospital of Castelfranco Veneto (Treviso), Italy.
authors.forename: D
authors.initials: D
authors.lastname: Rubello
authors.forename: P
authors.initials: P
authors.lastname: Gasparoni
authors.forename: G
authors.initials: G
authors.lastname: Rota
authors.forename: N
authors.initials: N
authors.lastname: Borsato
authors.forename: P
authors.initials: P
authors.lastname: Zanco
authors.forename: F
authors.initials: F
authors.lastname: Chierichetti
authors.forename: G
authors.initials: G
authors.lastname: Ferlin
mesh_terms: D000328:Adult; D001323:Autoantibodies / Q000032:analysis*; D005260:Female; D006801:Humans; D007453:Iodide Peroxidase / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D013670:Sodium Pertechnetate Tc 99m; D013961:Thyroid Gland / Q000000981:diagnostic imaging*; D013963:Thyroid Hormones / Q000097:blood; D013967:Thyroiditis, Autoimmune / Q000097:blood / Q000000981:diagnostic imaging* / Q000276:immunology; D013972:Thyrotropin / Q000097:blood; D014463:Ultrasonography
chemical_list: D001323:Autoantibodies; D013963:Thyroid Hormones; D013972:Thyrotropin; D013670:Sodium Pertechnetate Tc 99m; D007453:Iodide Peroxidase