Clinical Significance of Measurements of Antithyroid Antibodies in the Diagnosis of Hashimoto's Thyroiditis: Comparison with Histological Findings

Abstract

Measurements of antithyroglobulin and antimicrosomal (antiperoxidase) antibodies have been performed widely for the clinical diagnosis of autoimmune thyroid diseases. The present study was designed to compare these antibody titers with histological findings of the thyroid in patients with diffuse goiter who were suspected of having Hashimoto's thyroiditis. One hundred and ten euthyroid or hypothyroid patients (10 males and 100 females; age 48 +/- 15 (SD) years old) with diffuse goiter were studied for the measurement of antithyroglobulin and antimicrosomal or antiperoxidase antibodies by a hemagglutination technique (TGHA and MCHA, respectively) and by a newly developed radioassay (TgAb and TPOAb, respectively). The antibody titers were compared with the histological findings obtained by needle biopsy. TgAb, TPOAb, TGHA, and MCHA were detected in 80 (96.4%), 61 (73.5%), 37 (44.6%), and 54 (65.1%) of 83 patients with histologically proven Hashimoto's thyroiditis, respectively, but in only one (3.7%) of 27 patients without any inflammatory changes in the biopsy specimen. In 55 patients with negative TGHA and MCHA, the TgAb positivity was more closely associated with the histological diagnosis of Hashimoto's thyroiditis than the TPOAb positivity was, the incidence of each antibody in Hashimoto's thyroiditis being 89.7% (26/29) and 27.6% (8/29), respectively. In conclusion, the histological diagnosis of Hashimoto's thyroiditis can most precisely be predicted by the newly developed radioassay for TgAb.

Measuring thyroglobulin autoantibodies by sensitive assay is important for assessing the presence of thyroid autoimmunity in areas with high iodine intake

“…In addition, the prevalence of TgAb and TPOAb in the group of patients we studied was similar to the prevalence observed in the general population with the same assay methods [9], and the prevalence of FLT in the group of patients is also similar to the prevalence of focal thyroiditis observed in post-mortem tissue [10,11]. The presence of serum TgAb and/or TPOAb has been found to be associated with FLT in post-mortem tissue specimens [4] and biopsy samples from patients with enlarged thyroid glands [5]. The current study however has an advantage over these earlier reports as there was no age based bias (as in the case of post-mortem samples) or selection on the basis of large thyroid glands.…”

“…In this study, TgAb was thought to be the same or more closely related to the histological findings of autoimmunity than TPOAb and at least 8 patients with positive TgAb and negative TPOAb had histological findings of autoimmunity. While the analysis was performed using a different approach, with biopsy samples obtained from patients with goiter [5], and post-mortem thyroid tissue [4], it has been reported that a histological diagnosis of Hashimoto's thyroiditis can most precisely be predicted by radioimmunoassay for TgAb in comparison to TPOAb, and thyroglobulin antibody and microsomal antibody measured by hemmagutination technique in Japan. Baker et al reported that a cytologic diagnosis of Hashimoto's thyroiditis correlated better with antimicrosomal antibodies than with antithyroglobulin antibody titers, but those antibodies were measured by a hemagglutination technique, which is less sensitive than TgAb and TPOAb [6].…”

“…The prevalence of TgAb is higher than that of TPOAb in patients with Hashimoto's disease in reports from Japan [4,5], but not in the report from Europe [7]. …”

“…piration or needle biopsy specimens of thyroid glands of patients with enlarged thyroid gland [5,6]. The ideal approach to clarify this issue is considered to be to analyze the relationships among TgAb, TPOAb, and histological findings of thyroid in unselected living subjects, regardless of whether or not they have Hashimoto's disease.…”

Prevalência de auto-imunidade tireoidiana em um grupo de pacientes com diabetes mellitus tipo 1 em Londrina, PR

“…Esses mesmos autores sugerem como rotina no seguimento do DM1 a dosagem anual de anticorpos, com o objetivo de detectar o desenvolvimento inicial de tireoidite auto-imune. No caso de positividade, haveria indicação de avaliar a função tireoidiana e realizar ultra-sonografia de tireóide, com o objetivo de reduzir o risco de hipotireoidismo não diagnosticado em pacientes com DM1, visto que a disfunção tireoidiana não tratada pode influir negativamente no crescimento das crianças, dificultar o controle glicêmico e aumentar o risco de complicações macroangiopáticas do DM (21).…”