LAUSR

BACKGROUND Limited data are available for test utilization and intraindividual changes in anti-thyroid peroxidase antibodies (anti-TPO Ab) in Korean patients. METHODS Using a laboratory information system, we retrospectively investigated longitudinally measured anti-TPO Ab along with thyroid function test (TFT) in Korean patients visiting local clinics. RESULTS During the two-year study period, 542 test results from 183 Korean patients were requested from 51 local clinics and hospitals. Among all 183 patients, 94 (51.4%) exhibited positive anti-TPO Ab (> 34 IU/mL) at initial measurement. Among them, 13.8% (13/94) changed to negative anti-TPO Ab at least once during follow-up. Among 89 patients with initial negative anti-TPO Ab result, five (5.6%) changed to positive anti-TPO Ab at least once during follow up. CONCLUSIONS Some patients exhibited qualitative changes in anti-TPO Ab. Future studies are needed to clarify the clinical implication of such changes.