Sample stability:
-
14 days at 15-25 o C
-
14 days at 2-8 o C
-
24 months at -20 o C
External referrers: Please freeze samples at -20 o C and send frozen sample insulated and on ice.
NOTE: It is important to take the baseline specimen before a fine needle aspiration biopsy is performed. Damage to the thyroid gland may elevate thyroglobulin concentrations for at least 3 weeks.
Units: ug/L
| Normal range: |
less than 77 |
- Anti-thyroglobulin antibodies are often present in patients. These antibodies may interfere with the thyroglobulin measurement, causing falsely low and even undetectable results.
Uncertainty of Measurement: 8%
Principle: Sandwich type immunoassay with chemiluminescence detection
Reagents: Roche TG 2
Analyser: Cobas e801
Serum thyroglobulin (Tg) is increased in thyroiditis, goitre, thyroid trauma, hyperthyroidism, and thyroid carcinomas. Because elevated levels of Tg are non-specific it is not useful in the initial diagnosis of malignancy, but is useful in detection of recurrence (see below).
It is important to take the baseline specimen before a fine needle aspiration biopsy is performed. Damage to the thyroid gland may elevate Tg concentrations for at least 3 weeks. Surgery will elevate the concentration of thyroglobulin for at least two months; there is little value in collecting specimens for post-operative monitoring before then.
Following combination surgery and radioiodine ablation of thyroid carcinoma, serum Tg can be used to monitor recurrence, if the tumour originally secreted thyroglobulin . The sensitivity of Tg as a marker of recurence is increased by TSH stimulation, which can be achieved either by thyroxine withdrawal or by administration of recombinant human TSH. Guidelines have recommended that a serum Tg of greater than 2 ug/L (ref 1) or any detectable Tg (ref 2) after stimulation should prompt further investigation. Note that not all differentiated thyroid cancers secrete thyroglobulin, therefore it is important to know whether the pre-operative thyroglobulin was raised or not.
Inter-laboratory variation : significant variation exists between Tg assay methods. To ensure comparability, serial Tg measurements should be performed by the same laboratory.
References:
1. Mazziferri et al. A consensus report of the role of serum thyroglobulin as a monitoring method for low-risk patients with papillary thyroid carcinoma. J Clin Endocrinol Metab. 2003; 88: 1433-41.
2. Pacini F, Schlumberger M, Dralle H et al. European consensus for the management of patients with differentiated thyroid carcinoma of the follicular epithelium. Eur J Endocrinol. 2006;154:787-803
Emails to chemicalpathologist@adhb.govt.nz will receive priority attention from the on-call chemical pathologist.
If the query concerns a specific patient please include the NHI number in your email.
If email is not a suitable option, please contact the on-call chemical pathologist via Lablink (Auckland City Hospital ext. 22000 or 09-3078995).
Individual chemical pathologists may be contacted but will not be available at all times.
After-hours : contact Lablink (Auckland City Hospital ext. 22000 or 09-3078995) or hospital operator for on duty staff after hours.
Dr Samarina Musaad (Clinical Lead) : SamarinaM@adhb.govt.nz ext. 22402
Dr Cam Kyle: CampbellK@adhb.govt.nz ext 22052
Dr Weldon Chiu: WeldonC@adhb.govt.nz ext. 23427
Dr Campbell Heron: CHeron@adhb.govt.nz ext. 23427
Dr Sakunthala Jayasinghe: Sakunthala@adhb.govt.nz ext. 23427
Serum on cells can be analysed up to 48 hours post collection.
Stable for 48h at room temp, 72 h at 2-8 o C, or 30 days at -20 o C. Freeze once only .
Send separated serum (at least 300uL). Transport at room temp, or frozen if delay is likely to be more than 48 hours.