[131I-accumulating pulmonary and bone metastases of differentiated thyroid cancer with low serum thyroglobulin levels--an exception in tumor follow-up?].

In the follow-up of differentiated thyroid carcinoma it is discussed whether the tumor-marker thyroglobulin can replace the 131I scan, especially when the thyroglobulin serum level is normal. A positive 131I scan of metastases in the follow-up of patients with differentiated thyroid carcinoma combined with a low serum thyroglobulin level is extremely rare. The literature shows a frequency of about 4%. Recently we found 3 cases with a positive 131I scan demonstrating pulmonary and bone metastases whereas the serum thyroglobulin level was low.