Use of thyroglobulin as a tumour marker

Table 1 Interpretation and management of different serum thyroglobulin values

Stage of disease	Serum TG level			Uses and further action
	Low	Normal	Elevated
Before surgery	Anti-TGAb or TG non-secreting tumour			TG can not be used subsequently to monitor disease activity
			Benign or malignant thyroid disease	TG can be used subsequently to monitor disease activity
3-4 wk after surgery	Anti-TGAb, successful local surgery or no metastatic disease			Do 125-Iodine scan to screen for residual local disease and distant metastases
		Incomplete local surgery, metastatic disease or recurrence		Remnant ablation therapy (131-Iodine or further surgery) is indicated
Long term follow-up	Anti-TGAb			Do other tests to monitor disease activity
	Cure or stable disease			Disease activity can be monitored by periodic TG measurements
			Recurrence or progression	Further investigations and treatment

TG: Thyroglobulin; anti-TGAb: Autoantibodies against TG.