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PTD-301

Test Directory -  Thyroglobulin

Synonyms

TBG

Clinical Indications

Thyroglobulin (TG) measurement is useful in the evalutation of patients who have thyroid cancer, particularly follicular or papillary carcinoma of the thyroid. 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. 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.

Reference: Sheffield Protein Reference Unit (2013)

Request Form 

Combined Pathology Blood form (Yellow/Black or Blue for GP's)

Availability

Referral test: Analysed by Biochemistry, Protein Reference Unit, Sheffield, if specific criteria met.

Specific Criteria

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

Limitations

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.

Turnaround Time

3 weeks

Specimen

Serum

Volume

0.5 ml

Container


Yellow top (SST) tube


or red (plain) tube.

Collection

No specific collection conditions

Causes for Rejection

Unlabelled sample

Reference Range

1.4 - 78.0 ug/L.

Reference: Sheffield Protein Reference Unit (2013)

Interpretation

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.

Please note: as of 11.02.14 the method changed to Roche generation II sensitive thyroglobulin. Results > 1ug/L are up to 20% less than the previous assay and results should not be compared directly. The reference intervals remain the same. However, the functional sensitivity of the assay has improved with a lower limit now 0.04 ug/L.

Lab Handling

Processing: Aliquot (MPA) and store at 4°C in separating fridge (CB39), referral rack.
Referral
:  TBG and send or NOTBG and track at -20°C in separating freezer (CB40).

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Version 1.0 / July 2014                                                                                                           Approved by: Consultant Biochemist