Pathology Handbook

Thyroglobulin

Synonyms

Tg  (not to be confused with thyroid binding globulin, TBG)

Clinical Indications

Thyroglobulin is a sensitive marker of recurrent thyroid cancer following total thyroidectomy.

It is normally present in low concentrations in serum and increases in a range of thyroid diseases, including thyroid cancer, and is too non-specific to be of value in diagnosis.

Endogenous antibodies to thyroglobulin may invalidate the assay for serum thyroglobulin. Please contact the laboratory if thyroglobulin results do not correlate with clinical suspicion of recurrence, so that the sample can be checked for interfering antibodies.

Request Form 

Request on ICE

Availability

Analysed by referral laboratory if specific criteria met.

Specific Criteria

Monitoring for recurrent thyroid cancer following total thyroidectomy.

Turnaround Time

3 weeks

Specimen

Serum in plain red topped tube

SST samples are NOT suitable

Volume

2 ml

Container

Vacutainer red top

Collection

No specific collection conditions.

Sent to the Queen Elizabeth Hospital Birmingham, B15 2WB

Causes for Rejection

Unlabelled or inadequately labelled sample

Incorrect specimen tube

Request doe not meet specific criteria

Reference Range

Less than 5 µg/L.

After total thyroidectomy, thyroglobulin should no longer be detectable and measurable or rising concentrations imply the presence of thyroid tissue, presumably a recurrence of the cancer. Detection of recurrence may be made more sensitive by withdrawing replacement thyroxine therapy which causes TSH to rise.

Interpretation

Elevations may occur in untreated toxic nodular goitre, Grave's disease, acute and chronic thyroiditis.