Medizym® Tg is an ELISA assay for the sensitive and quantitative determination of human thyroglobulin (Tg) in serum.  Tg is produced by the follicular cells in the thyroid where they are retained.  Tg is used to produce the thyroid hormone T3 and T4.  Its presence in the circulation may be used as a tumor marker for papillary or follicular thyroid cancer.

  • Microtiter Plate. 12 breakable strips with 8 wells each (96 wells total) coat with mouse monoclonal anti-Tg antibodies.
  • Concentrate Wash buffer. 50 mL of 20x concentrated wash buffer
  • 14 mL of mouse monoclonal anti-Tg antibodies conjugated with HRP.  Ready to use
  • 14 mL of ready to use TMB
  • Stop solution. 14 mL of 1 N HCl.  Ready to use
  • Tg Calibrators. 7 vials of a protein-based buffer containing known concentrations of Tg
  • Tg Control. 1 mL of a protein-based buffer containing a known concentration of Tg

Biochemically, Tg is to be understood as a rather complex family of molecules. It is microheterogeneous with inter- and intraindividual variations (iodination degree, carbohydrat contents etc.). Dimers and several fragments also exist. Additional heterogeneity is due to malignant de-differentiation. Specifically and unspecifically interfering factors in individual sera cause further problems. Therefore, the Tg determination still represents a rather ambitious method.

On the other hand, Tg is the substratum of the thyroid hormone synthesis. Only thyroid tissue (even of malignant nature, if still differentiated) has the  ability to produce, to store and to secrete Tg. Consequently, Tg is organ- and tissue specific.

This is the basis for the main indication of the Tg determination (postoperative monitoring of differentiated thyroid carcinoma). Its paramount clinical value consists in the early detection and exclusion of metastases or tumor relapses and in the reliable follow-up of radioiodine treatments. Tg-profiles are of particular meaningfulness. After total thyroidectomy (and ablation by radioiodine) serum Tg is not detectable in those who are free of metastases and tumor (complete remission). Even under  endogenous TSH stimulation, Tg normally remains undetectable.

Detectable Tg values, however, are well accepted as important indication for neoplasia. Of particular significance are Tg values which are already detectable on TSH-suppressive thyroid hormone treatment or which show a steady increase during this drug regimen (Tg profiles). Another relevant criterion is a significant Tg increase after thyroid hormone withdrawal.

In the event, that any non-malignant thyroid remnants have been left, Tg is normally undetectable during TSH-suppressive thyroid hormone treatment. However, bigger remnants (> approx. 3 ml) or any co-existing non-malignant thyroid disease can lead in fact to detectable Tg. If the patient is on TSH stimulation, however, remnants as potential origin of measurable Tg have always to be taken into account.

In benign thyroid diseases, more or less elevated Tg values are regularly observed as compared to the reference range of healthy normal persons. Several factors (smoking, estrogenes, pregnancy, goitrogen drugs, iodine deficiency, TRAb etc.) and, in particular, disturbances of the morphological integrity of the gland (goitre, nodules, cellular destructions or thyroid autonomy etc.) act often complex and frequently lead to Tg elevations. Serum Tg is stimulated by TSH and is normally decreased by thyroid hormone administration (and iodine under certain circumstances, as well).