The value of serum thyroglobulin measurement in clinical practice
S. Refetoff and E. G. Lever
Thyroglobulin (TG) is a normal constituent of serum detectable by
radioimmunoassay in 75% to 90% of healthy adults. Levels are altered in a
number of physiological and pathological conditions. Although the
indications for serum TG measurements have not been clearly established, it
is simple, inexpensive, and presents no risk of radiation exposure.
Problems include variable sensitivity and reproducibility of assays,
interference by TG autoantibodies, and changes induced by certain
diagnostic or therapeutic interventions. Serum TG measurements is primarily
used as a tumor marker in thyroid carcinoma. Values are almost invariably
high with disseminated metastases. After total ablation of thyroid tissue,
serum TG determination is useful in separating patients in remission from
those with residual metastatic disease. Serial measurements in the same
patients are useful in monitoring the effect of treatment of nonfunctioning
thyroid metastases. It is of no proved value in the initial diagnosis of
thyroid carcinoma. Controversy still exists regarding the advantages of
measuring TG during hormonal therapy. The assay may aid in the diagnosis of
thyrotoxicosis factitia, painless subacute thyroiditis, and neonatal
hypothyroidism.
