Thyroperoxidase: A tumor marker for post-therapeutic follow-up of differentiated thyroid carcinomas? Results of a time course study

Serum thyroperoxidase (TPO) and serum human thyroglobulin (hTg) were studie d in 80 patients with differentiated thyroid carcinoma after thyroidectomy before and after the first therapeutic radioiodine application ("radioiodin e thyroid ablation") and, in some cases, after the second radioiodine appli cation. Eighteen patients with an autonomous adenoma were studied in the sa me manner. The values of TPO and hTg in 25 persons without thyroid impairme nt were used as controls. In 34 of 50 evaluable cases, TPO levels behaved a s hTg during follow-up studies: The majority (n=30) of these patients showe d an increase in TPO and hTg serum levels immediately after radioiodine the rapy, followed by a decrease approximately 3 days Inter. However, in 16 of 50 patients, the TPO and hTg serum levels showed different patterns of chan ge both before and after radioiodine therapy. In six of seven patients with extensive postoperative residues and high anti-hTg levels, distinctly elev ated TPO values were associated only by slightly elevated thyroglobulin val ues. There was no rise of TPO in autonomous adenoma except in patients trea ted with thyroid depressants. We assumed that TPO levels could serve as an "indicator" for destruction of thyroid cells or thyroid carcinoma cells and an aid in screening cases of false-negative hTg values.