Endocrine Abstracts

Thyroid ultrasound is a highly valuable tool for assessment of the thyroid volume, texture, echogenicity, and nodule evaluation and risk stratification. The method is preferably performed by the decision-making clinician. Due to the superficial location of the thyroid gland in the neck, the resolution of the ultrasound images is very high, and even small lesions in the thyroid can be detected. If a large part of the thyroid extends into the thorax, as can be seen in older individuals, this hinders a complete thyroid ultrasound examination. Thyroid autoimmunity, whether reflecting presence of autoimmune thyroiditis or Graves’ disease, appears hypoechogenic on ultrasound. The degree of hypoechogenicity correlates to some extent with plasma levels of thyroid autoantibodies. In Graves’ disease, the chance of remission can be predicted based on the ultrasound appearance, i.e., marginal/normal echogenicity, pseudonodularity, marked hypoechogenicity. In addition, assessment of the thyroid volume is highly valuable in assessing the chance of remission in Graves’ disease, in parallel with the thyroid echogenicity. The thyroid volume can be sonographically calculated from the ellipsoid formula, and with a reasonably precision unless the gland is grossly disconfigured due to thyroid nodularity. Thyroid planimetry is even more precise for volume estimation, but this method is rarely employed. Thyroid ultrasound can also be used to diagnose subacute thyroiditis, in which case the gland is tender, and ultrasound will show patchy avascular areas of marked hypoechogenicity in one or both thyroid lobes. Thyroid ultrasound, using the Doppler signal, may help differentiating between amiodarone-induced type 1 and type 2 thyrotoxicosis. the latter being an inflammatory condition.