Elecsys® Tg II

Elecsys TGII assay 01

The power to offer more in differentiated thyroid cancer (DTC) management

  • Thyroglobulin (Tg) is used to monitor patients after thyroid ablation
  • Tg is a glycoprotein with a molecular weight of approx. 660 kDa – it is synthesized in large quantities by the thyrocytes and released into the lumina of the thyroid follicles
  • Production of Tg is stimulated by TSH, intrathyroidal iodine deficiency and the presence of thyroid-stimulating immunoglobulins
  • Tg testing is mainly used during post-operative follow-up for patients with differentiated thyroid carcinoma (DTC)
  • As the thyroid gland is the only known source of Tg, the serum Tg level will drop to a very low or undetectable concentration after total thyroidectomy and radioiodine ablation of the residual thyroid tissue
  • For congenital hypothyroidism, Tg is used to distinguish between the complete absence of the thyroid gland and thyroid hypoplasia or other pathological conditions
  • It is also possible to distinguish between subacute thyroiditis and factitious thyrotoxicosis
Assay time 18 min
Sample material Serum, K2-EDTA plasma, K3-EDTA plasma
Sample volume 35 µL
Detection Limit * LoD 0.04 ng/mL, LoQ 0.1 ng/mL
Measuring range 0.04 - 500 ng/mL

*LoD = Limit of Detection; LoQ = Limit of Quantitation (<30 % total error).

Reliable performance for early detection of tumor recurrence

The Elecsys® TG II assay delivers benefits in a number of key areas:

Improved sensitivity and precision

  • Improved sensitivity comes with better precision in the range around the clinical cut-off and improved negative predictive value 
  • Sensitive Tg assays can avoid TSH-stimulated Tg testing during follow-up in low-risk patients1,2
  • Patients with a basal Tg below the functional sensitivity of a sensitive Tg assay have a high chance of being free of disease
  • Sensitive Tg testing combined with neck ultrasound provides a valuable method of identifying patients with or without recurrence for more reliable and accurate patient results around the clinical cut-off 3,4,6,7

Excellent technical assay performance

  • Excellent precision across the entire measuring range supports accurate results
  • Lot to lot consistency across all cobas platforms ensures reliable long-term patient monitoring
  • Elecsys Tg II shows lower TgAb interference compared to other assays 9 for high quality patient results and accurate long-term monitoring

Higher sensitivity allows for potentially earlier detection of persistence or recurrence

  • Increasing concentrations of Tg (even at low concentrations) are an early and reliable indicator of recurrent disease5
  • Treatment is usually more successful with early detection as the tumor burden is lower10
  • Changes in the Tg level are more important than single Tg results during monitoring.8
  • A Tg cut-off level >2 ng/mL following TSH stimulation is highly sensitive in identifying patients with persistent tumors2 – ensuring more time efficient diagnosis and treatment
References

1. Smallridge, R.C. et al. (2007). J Clin Endocrinol Metab 92, 82-87.
2. Cooper, D.S. et al. (2009). Thyroid 19, 1167-1214.
3. Spencer, C.A. & LoPresti, J.S. (2008). Nat Clin Pract Endocrinol Metabol 4, 223-233.
4. 4. Spencer, C.A. et al. (2010). Thyroid 20, 587-595.
5. Giovanella, L. (2008). Clin Chem Lab Med 46, 1067-1073.
6. Pacini, F. et al. (2006). Eur J Endocrinol 154, 787-803.
7. Castagna, M.G. et al. (2011). J Endocrinol Invest 34, e219-e223.
8. Iervasi, A. et al. (2007). Clin Endocrinol (Oxf) 67, 434-441.
9. Internal investigations (2012). Data on file.
10. Elisei, R. et al. (2012), A Nat Rev Endocrinol 8, 466–475 (2012); published online 3 April 2012.

Sensitive Tg assays can avoid TSH-stimulated Tg testing during follow-up in low-risk patients:
Smallridge, R.C. et al. (2007). J Clin Endocrinol Metab 92, 82-87.
Cooper, D.S. et al. (2009). Thyroid 19, 1167-1214.

Sensitive Tg testing combined with neck ultrasound provides a valuable method of identifying patients with or without recurrence:
Spencer, C.A. & LoPresti, J.S. (2008). Nat Clin Pract Endocrinol Metabol 4, 223-233.
Spencer, C.A. et al. (2010). Thyroid 20, 587-595.
Giovanella, L. (2008). Clin Chem Lab Med 46, 1067-1073.
Pacini, F. et al. (2006). Eur J Endocrinol 154, 787-803.
Castagna, M.G. et al. (2011). J Endocrinol Invest 34, e219-e223.

Increasing concentrations of Tg (even at low concentrations) are an early and reliable indicator of recurrent disease:
Giovanella, L. (2008). Clin Chem Lab Med 46, 1067-1073.

Treatment is usually more successful with early detection as the tumor burden is lower:
Elisei, R. et al. (2012 published online 3 April 2012). A Nat Rev Endocrinol 8, 466–475

During monitoring, changes in the Tg level are more important than single Tg results:
Iervasi, A. et al. (2007). Clin Endocrinol (Oxf) 67, 434-441.

A Tg cut-off level >2 ng/mL following TSH stimulation is highly sensitive in identifying patients with persistent tumors:
Cooper, D.S. et al. (2009). Thyroid 19, 1167-1214.