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.
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