Abstract: Objective: to observe the changes of serum thyroid peroxidase antibody (TPOAb) in the patients with Hyperthyroidism and Thyroid gland tumor in different phases. Methods: the levels of TPOAb were observed, the relation between the changed TPOAb level and reduced thyroid function was studied. Results: Amount 89 cases, there were 50 cases having normal or slightly elevated TPOAb level. However, after treatment, 31 cases presented a raised TPOAb level. Of 19 cases with hypothyroidism or its sub-clinical type. There were 39 cases with positive TPOAb. After the treatment, 2 cases changed to negative TPOAb, 26 cases lowered, and 3 cases had hypothyroidism. There were 29 cases taking thyroid tablets without appearance of hypothyroidism. Conclusion: the changes of TPOAb level can be observed during the treatment for hyperthyroidism and t hyroid gland tumor. The elevated TPOAb level often predicts the decreased thyroid function. The patients with positive TPOAb should be concerned, and for hyperthyroidism patients the treatment should be taken with care.

Key words: hyperthyroidism, thyroid gland tumor, thyroid peroxidase antibody, hypothyroidism