Diagnostic usefulness of thyroid ultrasonography in atrophic thyroiditis.

An abnormal thyroid echographic pattern, characterized by a diffuse low thyroid echogenicity associated with a reduced thyroid volume, was found in 53 of 55 (96%) patients with atrophic thyroiditis. In 10 of these patients, the ultrasound examination was diagnostic for thyroid atrophy, whereas the scintiscan had no abnormality. In only two cases was the reverse observed, ie, absent thyroid radioiodine uptake and no evidence of abnormality in the ultrasound examination. Six out of 24 (25%) patients with thyroperoxidase antibody titers < or = 1:1600 and 4 of 31 (13%) patients with titers > or = 1:6400 had a normal thyroid scintiscan in the presence of an abnormal thyroid echographic pattern. Thus, thyroid echography can be considered the first morphological procedure in patients with hypothyroidism due to atrophic thyroiditis, and thyroid scintiscan can be used to confirm the diagnosis when other results are not definitive.