| Interpretive Data: |
Thyroglobulin (Tg) is measured by the Beckman Access method, which has a lower limit of quantification of 0.1 ng/mL. Results obtained with different assay methods or kits cannot be used interchangeably. The Tg result, regardless of concentration, should not be interpreted as absolute evidence for the presence or absence of papillary or follicular thyroid cancer and is not recommended for use as a screening procedure to detect the presence of cancer in the general population.
Tg antibodies (Tg Ab) are known to interfere with the measurement of Tg. In patients with positive Tg Ab results (greater than 14.4 IU/mL), a recovery study is performed. A recovery of less than 80% in any sample suggests a Tg Ab interference so the Tg concentration cannot be accurately quantified. A Tg result of greater than or equal to 0.1 ng/mL, in the presence of a positive Tg Ab result, qualitatively indicates that Tg is present in the specimen.
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