Thyroid Cancer Monitoring
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Definition / Purpose:  Thyroglobulin measurements are most useful in the postoperative monitoring of patients with papillary, follicular, and Hurthle cell carcinomas. However, approximately 20% of individuals develop autoantibodies to thyroglobulin. Since these antibodies interfere with immunoassay measurement of thyroglobulin, it is necessary to determine the presence or absence of antibodies before measuring thyroglobulin. 
Reference Range(s)
Thyroglobulin Antibody≤1 IU/mL
Thyroglobulin<0.1 ng/mL
Thyroglobulin, LC/MS/MS<0.4 ng/mL

When to order:  Monitoring post thyroid cancer surgery

Pearl: If Thyroglobulin Antibody is negative, then Thyroglobulin is tested on the Beckman Coulter DxI. If Thyroglobulin Antibody is positive then, Thyroglobulin is tested by LC/MS/MS