Thyroglobulin

Immunology

---

Description

The main application of all tumour markers is monitoring for relapse or progression. Use as a diagnostic aid requires care and knowledge of the test limitations. Opportunistic screening is discouraged. Thyroglobulin (TG) is a heterogeneous iodoglycoprotein which has a molecular mass of approximately 660,000 daltons [2]. It is sythesised in the follicular cells of the thyroid gland. TG measurement is useful in the evaluation of patients who have thyroid cancer, particularly follicular or papillary carcinoma of the thyroid [1]. Guidelines set out by the British Thyroid Association state that TG should be used for post-operative follow-up of patients, and pre-operative results have no diagnostic or prognostic value [3]. The reappearance of circulating TG after total thyroid ablation is a sign that there is thyroid tissue remaining and may indicate that a tumour is still present [4]. TG may also be of use in the differential diagnosis of congenital hypothyroidism, and in helping to distinguish subacute thyroiditis from thyrotoxicosis caused by covert administration of thyroid hormones. In the latter event, low levels of thyroglobulin are expected due to thyroid hormone suppression of thyrotropin [5].

---

Indications

Identification of the presence of functioning thyroid tissue post-thyroidectomy. Follicular or papillary thyroid carcinoma.

---

Sample Type

2mL Serum (Gel 5mL Yellow tube). Requests from outside Sheffield: Transport at ambient temperature via Royal Mail or Courier.

---

Reference Range

1.4 - 78 ug/L.Higher values are encountered in newborns and during the third trimester of pregnancy.Reference ranges established in house and PRU collaboration.

---

Turnaround Time

Within 2 days

---

Testing Frequency

Daily

---

External Notes

Tumour markers are not diagnostic and are of most use in monitoring response to treatment and early detection of relapse. Normal values do NOT exclude malignancy. Quoted ranges only valid for serum.

---

References

Lin J-D. Thyroglobulin and human thyroid cancer. Clin Chem Acta. 2008. 388:15-21. [Ref 1]PRU Handbook of Clinical Immunochemistry. 9th Edition. 2007. [Ref 2]British Thyroid Association. Guidelines for the management of thyroid cancer. 2nd edition. 2007. [Ref 3]Whitley RJ, and Ain KB. Thyroglobulin: a specific serum marker for the management of thyroid carcinoma. Clin Lab Med. 2004. 24(1):29-47. [Ref 4]Grossman A. Clinical Endocrinology. 2nd Edition. 1998. [Ref 5]

---

See Also

Thyroglobulin antibodies

Please note: the above information is subject to change and we endeavour to keep this website up to date wherever necessary.