Thyroid related

Author: Nat Pernick, M.D. (see Authors page)

Revised: 23 February 2016, last major update March 2011

Copyright: (c) 2002-2016,, Inc.

PubMed Search: Thyroglobulin [title]
Table of Contents
Definition / General | Laboratory
Cite this page: Thyroglobulin. website. Accessed October 21st, 2016.
Definition / General
  • Prohormone of T3 and T4 synthesized by thyroid follicular cells and cosecreted into serum with T3 and T4
  • Serum level is affected by thyroid mass, thyroid injury and TSH receptor stimulation
  • Tyrosine residues of thyroglobulin are iodinated with thyroid peroxidase to produce mono- and diiodotyrosyls, which combine to form T3 (mono+di) and T4 (di + di)
  • Thyroglobulin releases T3 and T4 into circulation via lysosomal degradation
  • Used primarily to monitor recurrence of well differentiated thyroid cancer after total thyroidectomy or I-131 treatment (Endocr Regul 2006;40:53)
  • Also to diagnose thyroid dysgenesis in congenital hypothyroidism (J Med Genet 2005;42:379) or to distinguish subacute thyroiditis (elevated levels) from factitious thyrotoxicosis (undetectable levels despite elevated T3 and T4 levels)

  • Immunoassay

Monitoring recurrence of well differentiated thyroid carcinoma
  • Give patient recombinant human TSH, and measure thyroglobulin 72 hours after last dose
  • Rise of serum thyroglobulin above 2 ng/ml (if had remnant ablation and receiving hormone suppressive therapy) correlates with presence of recurrent disease
  • Can confirm recurrent disease by whole body iodine scan
  • Well differentiated tumors typically have 10x rise in thyroglobuln
  • Poorly differentiated tumors may not concentrate iodide, may have blunted response to TSH stimulation
  • Can also monitor change of thyroglobulin level when receiving T4 treatment post-thyroidectomy (J Clin Endocrinol Metab 2005;90:5047)

  • 20% with thyroid cancer have antithyroglobulin antibodies which interfere with assay (falsely lower serum concentration by binding to thyroglobulin and making it "invisible" to the assay)
  • Should determine presence of antibodies when measure thyroglobulin level for tumor monitoring
  • If antibodies are present, PCR may be useful to measure thyroglobulin
  • Also interference by heterophile antibodies (J Clin Endocrinol Metab 2003;88:3069)

Reference range
  • < 30 ng/ml (45 pmol/L)

High values
  • Graves disease, thyroiditis, nodular goiter, well differentiated thyroid carcinoma

Low levels
  • Factitious thyrotoxicosis (surreptitious use of thyroid hormone-levels are undetectable although T3 or T4 are elevated)