Correlation of antithyroglobulin and antithyroid-peroxidase antibody profiles with clinical and ultrasound characteristics of chronic thyroiditis

Patients with chronic thyroiditis were selected for study according to spec ific selection criteria, and comparisons of an enzyme-linked immunosorbent assay (ELISA) method to a hemagglutination method were performed. The ELISA assays contained antithyroglobulin (TG) antibody and antithyroid-peroxidas e (PO) antibody, the latter using recombinant human TPO. Four groups were e stablished from 437 patients with chronic thyroiditis; 316 with both antibo dies (TG + PO group), 75 with TG antibody alone (TG group), 10 with PO anti body alone (PO group), and 36 with no such antibodies (N group). The hemagg lutination assay resulted in much different antibody profiles: PO group bas ed on ELISA occurred in only 2%, whereas a group with microsome antibody al one based on hemagglutination assay occurred in 39%. Subsequently, studies of disease characteristics including age, gender, familial predisposition, thyroid function, and morphology of the gland were performed among the four groups of patients based on ELISA profiles but not on hemagglutination res ults. The subgroups of TG + PO and TG were derived from randomly selected p atients (40 out of a much larger number of patients in each). The results s howed that the PO group had smaller thyroid volume (25 +/- 16 mL, mean +/- SD) with normal echogenicity, and 50% prevalence of hypothyroidism. The TG group had larger thyroid volume (57 +/- 42 mL) with frequent association of small nodular formation (53%) but less frequent hypothyroidism (23%). In s ummary, compared to the hemagglutination method, the ELISA was noted to hav e both a higher sensitivity and specificity for detection of chronic thyroi ditis. Correlation of ELISA profiles with ultrasonography of the thyroid gl and detected subtle differences in subgroups that may account for differenc es in thyroid gland morphology and prevalence of hypothyroidism: the PO gro up has normal echogenicity but high incidence of impaired thyroid function, whereas in the TG group small nodules were associated with a lesser incide nce of hypothyroidism.