Medizym® Tg Rem

• Microtiter Plate. 12 breakable strips, each with 8 wells (96 wells total) coated with monoclonal mouse anti-hTg antibodies.  The plate is stored in a vacuum sealed bag with desicant
• Concentrated Wash Buffer. 125 mL of 10x wash buffer concentrate
• Sample Diluent. 100 mL of ready to use sample dilution buffer
• Vial containing sufficient lyophilized material for 20 mL of monoclonal mouse anti-hTg antibody conjugated to HRP
• Conjugate Diluent. 25 mL of ready to use dilution buffer for conjugate antibody
• 12 mL of ready to use TMB
• Stop Solution. 12 mL of 0.25 M sulfuric acid.  Ready to use
• Mouse IgG. 4 mL of ready to use mouse antibody.
• Recovery test sample. Sufficient material for 1.5 mL of serum diluted control with 5 ng Tg/mL
• Tg Calibrator 0. 1 mL of Tg-free serum.  Ready to use
• Tg Calibrators 1-8. 1 mL each 8 different known concentrations of Tg in sera.  Ready to use.
• Tg Control Sera. 1 mL of serum with a known concentration of Tg.  Ready to use.

Biochemically, Tg is to be understood as a rather complex family of molecules. It is micro heterogeneous with inter- and intra-individual variations (iodination degree, carbohydrate 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 (postope-rative 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 anymore in patients 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 still existing or newly developed 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 (goiter, 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).