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Thyroglobulin, Body Fluid (FNA)
(Not a routinely available test. See 'Additional information')
|Test group||Thyroid tests|
|Performed by||Parnassus Chemistry|
|In House Availability||Tuesday, Friday (day shift)|
|Method||Immunoenzymatic assay (Beckman Access assay on UnicelDxI 600)|
|Collection Instructions||Submit fine needle aspiration (FNA) samples suspended in 1.0 mL (20 drops) of saline in a sterile tube. Each sample should be labeled with an identifier and the same information listed below to allow for proper identification of sample(s) on lab reports.
Deliver immediately to laboratory
|Container type||Sterile tube (see collection instructions)|
|Amount to Collect||1.0 mL (see collection instructions)|
|Sample type||Fine needle aspirate fluid or tissue aspirate|
|Preferred volume||1 mL fluid|
|Min. Volume||0.5 mL fluid|
|Processing notes||Centrifuge sample and refrigerate.|
|Synonyms||TGB; TGLB; Tg; Thyroid cancer|
|Stability||Room temperature 8 hours, refrigerated 1 week, frozen 1 month|
|Turn around times||1-5 days|
|Additional information||As normal samples are not available for validating the performance of this assay, the UCSF Clinical laboratory makes no claims with regard to the accuracy of the result.
All results will be appended with a disclaimer: "The reference range and other method performance specifications have not been established by the UCSF Clinical Laboratory for this body fluid. The test result must be integrated into the clinical context for interpretation."
Measurement of thyroglobulin in lymph node aspirates may be useful for diagnosis of metastatic differentiated thyroid cancer. In a study of 190 malignant lymph nodes, and 338 benign lymph nodes, the median FNA-Tg was 521.2 (3676.8) ng/mL in the malignant LNs, and 0.1 (0.2) ng/mL in the benign LNs. The optimal cutoff value of FNA-Tg in distinguishing malignant LNs from benign LNs was 1.0 ng/mL (sensitivity, 93.2%; specificity, 95.9%). Moon et al, J Clin Endo Metab, March 2013.
Note that the presence of anti-TG antibodies may tend to decrease results of TG measurements. The extent to which the presence of anti-TG antibodies interferes in the assessment of FNA-TG measurements is unclear. Some, but not all, investigators have suggested that FNA-TG results are still useful even in the presence of anti-TG antibodies. Cunha et al, European Journal of Endocrinology (2007) 157 101–107.
In this Beckman Access assay on the UnicelDxi 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 ClinEndocrinolMetab 2011). Results below 0.1 µg/L are reported as < 0.1 µg/L.
|LDT or Mod FDA?||Yes|
|Last Updated||6/2/2016 3:22:42 PM|