Thyroglobulin (Tg) is produced exclusively in the thyroid gland. In cases of thyroid carcinoma where the thyroid gland is surgically removed, Tg levels fall to non-detectable levels. In such cases, Tg may serve as a tumor marker and can be monitored on a regular basis for evidence of detectable levels, as any detectable level would indicate the possibility of a tumor that is producing Tg.
Methods for the analysis of Tg typically employ immunoassay principles and the more sensitive methods, using chemiluminescence, are used as indicators (tumor growth) of thyroid tissue. It is essential to measure thyrogloblin antibody (TgAb) when measuring Tg, as the presence of TgAb invalidates the accuracy of Tg levels, as determined by immunoassay. In such cases, chromatographic methods should be sought for accurate Tg determination.