Is there any venous gradient in serum thyroglobulin levels in patients with differentiated thyroid cancer?

Abstract

Some patients with differentiated thyroid cancer (DTC) have high serum thyroglobulin (Tg) levels although no evidence of disease can be detected on radioiodine scanning or other imaging methods. The aim of this study is to determine whether a gradient exists between the Tg levels of venous samples adjacent to primary tumour and systemic circulation. Twenty-six patients underwent thyroidectomy and/or lymph node dissection for primary and recurrent DTC. To detect Tg levels, blood samples were concurrently collected via venipuncture from the internal jugular vein adjacent to the tumor and ipsilateral antecubital vein. Serum Tg level was measured by a chemiluminescence assay. Tg levels were significantly higher in the adjacent internal jugular vein compared to the ipsilateral antecubital vein (p=0.001). The ratio of mean Tg values was higher 2.4-fold in the internal jugular vein than antecubital vein (median Tg ratio: 2.0:1; range, 0.7-29.6). Documentation of a venous gradient in Tg levels in patients with DTC is a new investigational topic. According to the results of this prospective study, venous sampling for Tg may be a useful tool to localize recurrent or perhaps persistent DTC in the neck for patients who have no detectable disease on radioiodine scans or other imaging studies.