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Thyroglobulin, Ultrasensitive (Tumor Marker; includes anti-Tg Ab testing)
|Test Update Information||Test introduced effective March 19, 2013. All orders for thyroglobulin testing starting March 19, 2013 are performed using this highly sensitive assay.|
|Utilization Guidelines||This test is reserved for monitoring patients s/p thyroidectomy. It is not for use in measuring Thyroglobulin levels in patients with intact thyroid glands.|
|Test group||Thyroid tests|
|Performed by||Parnassus Chemistry|
|In House Availability||Tuesday, Friday (day shift)|
|Method||Immunoenzymatic assay (Beckman Access assay on Unicel DxI 600)|
|Container type||Red top or Gold top|
|Amount to Collect||3 mL blood|
|Preferred volume||1.1 mL serum|
|Min. Volume||1.0 mL serum|
|Processing notes||Refrigerate serum.|
|Normal range|| Thyroglobulin:
*Reference range was adopted from reagent vendor (Abbott Labs) performed studies and verified in house by running 21 male samples less than 30 years of age with a TSH level between 0.5-2.0 mIU/L. This selection criteria is specified in the NACB: Laboratory Support for the Diagnosis and Monitoring of Thyroid Disease guidelines.
|Stability||Room temperature 8 hours, refrigerated 2 days, frozen -20C 1 month|
|Turn around times||Test performed 6x per week. Turnaround time 4-6 days|
|Additional information||Note: Samples tested for thyroglobulin will automatically be screened for the presence of thyroglobulin antibodies using a sensitive assay for anti-thyroglobulin antibodies (see TGLB Antibodies, test code TGAB). The presence of anti-thyroglobulin antibodies can interfere in this thyroglobulin assay and may cause falsely decreased results.
Thyroglobulin results obtained with this assay should not be compared to results generated with other thyroglobulin assays owing to differences in assay design and calibration.
In this Beckman Access assay on the Unicel Dxi platform, the functional sensitivity defined as the lowest value that can be measured in thyroglobulin-negative antibody serum with a 20% coefficient of variation has been verified in house and in other laboratories to be < 0.1 µg/L (Malandrino et al, J Clin Endocrinol Metab 2011). Results below 0.1 µg/L are reported as < 0.1 µg/L
Thyroglobulin levels are useful to assess the presence of residual differentiated thyroid carcinoma. Athyrotic individuals should have extremely low to undetectable levels of thyroglobulin. Increasing levels indicate possible recurrence or metastasis. Levels are not elevated in medullary or anaplastic thyroid carcinomas nor with small tumors, and are generally not useful as a routine screening test for thyroid cancer.
Normal reference ranges were adopted from the literature and verified in house by measuring thyroglobulin in serum from 138 healthy blood donors with normal TSH levels and negative for anti-thyroglobulin antibodies and anti-TPO antibodies (Giovanella et al. Clin Chem Lab Med, 2011).
|CPT coding||Thyroglobulin Ab Screen 86800-90
Thyroglobulin , Tumor Marker 84432-90
|Last Updated||3/19/2013 10:06:58 AM|
If you have additional questions regarding this test, please call: 415-353-1667