Patient selection: total thyroidectomy for thyroid cancer with I131 ablation
Risk for recurrence:
(1) poorly differentiated or aggressive histology
(2) local lymph node metastases (N1)
Ideally serum thyroglobulin should:
(1) be elevated prior to initial therapy
(2) become undetectable after total thyroidectomy
(3) then rise with recurrence.
Risk factors for failure in thyroglobulin monitoring:
(1) poorly differentied thyroid cancer that produces little thyroglobulin
(2) antithyroid antibodies
(3) change in testing methodologies
Monitoring a patient with a history of thyroid cancer:
(1) serial measurement of serum thyroglobulin using a high-sensitivity assay at the same laboratory using the same method
(2) TSH stimulation (with recombinbinant human TSH) may increase sensitivity and avoids the need to discontinue thyroxine replacement therapy
(3) perform ultrasound for lymph nodes in the neck
(4) measure titers of antithyroglobulin antibodies if present (over time these should disappear or become low titer if there is no recurrent disease; titers will not fall or will rise with recurrent disease)
(5) whole body and PET scans should be reserved for high risk patients or for patients with evidence of recurrence
