title: Effect of L-thyroxine administration on antithyroid antibody levels, lipid profile, and thyroid volume in patients with Hashimoto's thyroiditis.
abstract: The changes in the serum thyroid autoantibodies, antithyroglobulin (TgAb) and antithyroid-peroxidase (TPOAb), lipid profile, and thyroid volume following L-thyroxine (L-T4) therapy is still a controversial matter. We studied 23 patients with goiter due to Hashimoto's thyroiditis; 10 had clinical hypothyroidism (CH) and 13 had subclinical hypothyroidism (SH). Both groups received L-T4 (2.0 to 2.5 micrograms/kg/day) for a median period of 6 months. Serum concentration of TgAb (normal value: < 200 mUI/mL) and TPOAb (normal value: < 150 mUI/mL) were measured by a sensitive IRMA using 125I protein-A. Thyroid volume was determined by ultrasound (normal value: 8-14 mL). At the end of the observation period the median serum TSH concentration decreased significantly in both groups (42.9 to 0.55 in CH and 2.4 to 0.74 mU/L in SH patients) and serum FT4I levels increased only in the CH group (0.87 to 2.1; p < 0.05). Serum TgAb concentration did not change in SH patients (72 to 218 mUI/mL) but declined in CH patients (364.5 to 75 mU/mL; p < 0.05). TPOAb levels also fell in the CH group (871 to 194 mUI/mL; p < 0.05) and no significant change was noted in SH patients (260 to 116 mUI/mL). Further, a significant correlation was obtained between TSH and either TPOAb concentration (rs = 0.569, p < 0.01) or thyroid volume (rs = 0.488, p < 0.05) in the CH group but not in SH patients (rs = 0.232, NS). LDL-cholesterol was higher in the CH (159.4 mg/dL) compared with the SH group (116 mg/dL). Moreover, only in the CH patients was there a significant fall in total cholesterol (224.5 to 165.5 mg/dL, p < 0.05) and in LDL-cholesterol (159.4 to 104.3 mg/dL, p < 0.05) values. The thyroid volume decreased in all patients with CH and in 77% (10/13) of SH patients and a significant median in the thyroid volume decrease was found (39.7% of initial volume in the CH group and 80.9% in SH patients; p < 0.01). The influence of L-T4 on both thyroid autoantibody levels and thyroid volume might be explained by reduction of antigenic substance through a decreased stimulation of thyroid tissue by circulating TSH as was seen in CH but not in SH patients. The benefits of the administration of L-T4 replacement therapy in SH patients due to Hashimoto's thyroiditis remain to be clarified.
authors.affiliation: Department of Endocrinology, Hospital do Servidor Publico Estadual-IAMSPE, São Paulo, Brazil.
authors.forename: J H
authors.initials: JH
authors.lastname: Romaldini
authors.forename: M M
authors.initials: MM
authors.lastname: Biancalana
authors.forename: D I
authors.initials: DI
authors.lastname: Figueiredo
authors.forename: C S
authors.initials: CS
authors.lastname: Farah
authors.forename: P C
authors.initials: PC
authors.lastname: Mathias
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000097:blood*; D008078:Cholesterol, LDL / Q000097:blood; D005260:Female; D006801:Humans; D008055:Lipids / Q000097:blood*; D008297:Male; D008875:Middle Aged; D013954:Thyroglobulin / Q000276:immunology; D013961:Thyroid Gland / Q000000981:diagnostic imaging / Q000276:immunology* / Q000473:pathology*; D013967:Thyroiditis, Autoimmune / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000276:immunology; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use*; D014463:Ultrasonography
chemical_list: D001323:Autoantibodies; D008078:Cholesterol, LDL; D008055:Lipids; C056626:thyroid microsomal antibodies; D013972:Thyrotropin; D013954:Thyroglobulin; D013974:Thyroxine