High TPOAb Levels (>1300 IU/mL) Indicate Multifocal PTC in Hashimoto's Thyroiditis Patients and Support Total Thyroidectomy.

Abstract

We aimed to identify whether thyroid peroxidase antibodies (TPOAb) are indicative of multifocal papillary thyroid cancer (PTC) in Hashimoto's thyroiditis (HT) patients and may help to determine necessity for total thyroidectomy. Retrospective cohort study. Teaching hospital. A total of 808 consecutive patients with HT alone or with HT and unifocal or multifocal PTC were included. Preoperative thyroid function tests, TPOAb determination, preoperative ultrasonography, intraoperative frozen biopsy, and postoperative routine pathologic examination to confirm thyroid nodules were performed for all patients. Patients with nodules or malignancy potential on ultrasound and fine-needle aspiration cytology were included. Patients with hyperthyroidism, concomitant chronic disease, a history of other malignant tumors, or history of major diseases were excluded. All patients underwent surgery, and HT and PTC were confirmed by postoperative pathologic results. No significant differences were found in age and sex between groups (P > .05). TPOAb ≤1300 IU/mL were more prevalent in the HT + unifocal PTC group than in the other groups (99.57% vs 15.52% and 60.75%, P < .001). TPOAb >1300 IU/mL were more prevalent in the HT + multifocal PTC group than in the other groups (84.48% vs 0.43% and 39.25%; P < .001). Compared to the other groups, the HT + multifocal PTC group had higher percentages of patients with elevated thyroid-stimulating hormone and positive central lymph node (LN) metastasis (elevated thyroid-stimulating hormone: 8.7% vs 3.2% and 6.5%, P = .008; positive central LN metastasis: 74.57% vs 67.38% and 0%, P < .001). High TPOAb levels (>1300 IU/mL) are definitive indicators of multifocal PTC in HT patients, which may support surgical treatment with total thyroidectomy.