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I am an argentine Endocrinologist at the German Hospital in Buenos Aires, Argentina. I would appreciate your advice on the following clinical case. We are treating a 28 years old man, who underwent a total thyroidectomy and radical neck limphadenectomy due to thyroid carcinoma and elevated antithyroglobulin antibodies levels (245.5 IU/ml (normal: 0.0-115) ) in October, 2004.
Pathological study: Papillary thyroid carcinoma, common cell type, 1.8cm diameter, extracapsular extension to soft perithyroid tissues. Metastasis in 5 homolateral cervical limph nodes. pT2aN1a
Lab tests after surgery, pre I131 without T4 (Noviembre de 2004): TSH: >100 mcU/ml T4: 0.7 mcg/dl, Serum thyroglobulin: 0.2 ng/ml, Antithyroglobulin antibodies: 414.3 UI/ml.
Scan pre and post ablative doses of I131 (Noviembre de 2004): uptake in neck (8 mm image)
Patient starts treatment with T4.
Lab tests (February 2005): TSH: 0.06 mcU/ml, T4: 10.1 mcg/dl, Serum thyroglobulin: < 0.2 ng/ml, Antithyroglobulin antibodies: 333.4 UI/ml.
Lab tests pre scan without T4 (June 2005): TSH: >100 mcU/ml, T4: 0.5 mcg/dl, Serum thyrogloublin: 0.2 ng/ml, Antithyroglobulin antibodies: 267.2 UI/ml
In the current exams, there are no other abnormal images in body scans, but patient keeps having high levels of antithyroglobulin antibodies.
Should we continue with I131 therapy for that image? If not, should we wait until those levels go down? If so, how much time should we wait? Thank you very much for your time and help.
Mar'a P'a Lozano, MD
Response
At present the TG levels are probably meaningless, with strong antibody levels present. If all thyroid tissue is removed, in theory the antibodies should decline gradually, but the time is measured in years. Your patient has some tissue remaining, and this may be enough to maintain auto-immunity. You can follow the patient with ultrasound and 131-I scan, and I suppose PET scanning is possible. Alternatively, if the thyroid tissue was ablated, the antibody level might decline. Considering the extra-thyroidal invasion and positive nodes, my personal view is that aggressive follow-up is appropriate.
L DeGroot, MD