One Thyroglobulin Test Can be Predictive of Future Thyroid Cancer Metastases

Researchers reporting in the Journal of Clinical Endocrinology & Metabolism were evaluating the accuracy of a single recombinant human (rh)TSH-stimulated serum thyroglobulin (Tg) test -- this is a thyroglobulin test while on the drug Thyrogen. Thyrogen is a drug that enables thyroid cancer patients to avoid having to withdraw from all thyroid hormone drugs, and become hypothyroid in preparation for a scan.

The researchers looked at 107 differentiated thyroid cancer patients, and separated them according to their initial rhTSH-Tg levels. Group 1 had a Tg less than 0.5, group 2 had Tg of 0.6–2.0, and group 3 had a Tg greater than 2. The patients were evaluated over the period of a year to five years, and Tg was measured during thyroid hormone suppression, after rhTSH and/or after complete thyroid hormone withdrawal.

What they discovered was that in 81% of those patients who had an initial or follow-up rhTSH-Tg greater than 2, tumor was found. The researchers concluded that:

"A single rhTSH-Tg greater than 2 ng/ml predicts persistent tumor, although no value entirely excludes future recurrence."

Patients at risk of recurrence, and especially those who had an rhTSH-Tg greater than 1, should get repeated TSH-stimulated testing.

Patients who had a rhTSH-Tg less than 0.5 ng/ml without Tg antibody are so unlikely to have a recurrence that "frequent imaging and TSH-stimulated Tg testing are unnecessary."

Source: Kloos and Mazzaferri, "A Single Recombinant Human Thyrotropin-Stimulated Serum Thyroglobulin Measurement Predicts Differentiated Thyroid Carcinoma Metastases Three to Five Years Later" The Journal of Clinical Endocrinology & Metabolism Vol. 90, No. 9 5047-5057. See PubMed abstract