Thyroid Research Thyroid Research Archive Thyroid Cancer

Serum thyroglobulin values vary according to number and site of metastatic tumor in patients with thyroid carcinoma

(March 2005)

The background of the study. Measurement of serum thyroglobulin (Tg) is the most sensitive test for persistent or recurrent thyroid carcinoma. This study was undertaken to determine the relationships between basal and thyrotropin (TSH)-stimulated serum Tg values and tumor volume and location in patients with thyroid carcinoma.

How the study was done. The study subjects were 417 patients with thyroid carcinoma who had been treated by thyroidectomy and radioactive iodine (I-131) and then thyroxine. For each patient, the pathological diagnosis was confirmed, serum Tg was measured before and after the administration of two doses of TSH, and a whole-body diagnostic I-131 scan was done. Many patients also underwent ultrasonography of the neck and other imaging tests. Based on the results of these studies, the patients were categorized as having no tumor, a thyroid remnant or tumor limited to the thyroid bed, and tumor outside the thyroid bed.

The results of the study. Among the 417 patients, 48 percent had no evidence of persistent or recurrent tumor, 11 percent had a thyroid remnant or tumor in the thyroid bed, and 41 percent had a tumor in a bone, the chest, or the neck. Patients with tumor in a bone had the highest basal serum Tg values, followed by those with tumor in the lung and lymph nodes in the neck. Overall, serum Tg values were correlated with the extent of tumor, and in most patients with very high values the tumor had spread to multiple sites. The increase in serum Tg values after TSH stimulation varied considerably, and it correlated poorly with the volume or site of metastases.

The conclusions of the study. In patients with thyroid carcinoma that has spread to other organs, basal serum Tg concentrations are correlated with the extent and site(s) of the tumor.

The original article. Robbins RJ, Srivastava S, Shaha A, Ghossein R, Larson SM, Fleisher M, Tuttle RM. Factors influencing the basal and recombinant human thyrotropin-stimulated serum thyroglobulin in patients with metastatic thyroid carcinoma. J Clin Endocrinol Metab 2004;89:6010-6.