Effect of Levothyroxine Therapy on Thyroid Peroxidase Antibody Level in 20-50 year old females with Hashimoto's disease

Hashimoto's thyroiditis is the most prevalent cause of hypothyroidism in children and adults. The disease clinically manifests itself in three forms namely hypothyroidism, euthyroidism, and hyperthyroidism. The present study was carried out aiming at determining anti-thyroid peroxidase antibody variation before and after levothyroxine treatment in hashimoto's thyroiditis patients. In this quasi-experimental study, at first patients with firm goiter referring to Birjand glands deficiency clinic between 2005 and 2006 were examined, and those with positive anti- TPO antibody were accounted as hashimoto cases. Then, these cases were prescribed a three- month treatment with 100 microgram daily of levothyroxine. At the end of the period, their level of anti- TPO antibody was measured and their clinical conditions were assessed. The obtained data was then analysed by means of SPSS software statistical tests including independent t, paired t test and chi-square test. Majority (67.1%) of the patients were diagnosed as hypothyroid, and 32.9% were euthyroid cases. The level of anti-TPO antibody in 20% of the patients reached normal level after a period of three month treatment with levothyroxine. Mean anti-TPO antibody level before levothyroxine treatment was 450.74±122.05 IU/mL, which reduced to 236.2±153.96 IU/mL after treatment (P<0.001). Mean anti-TPO antibody level before treatment was higher (P<0.001) in hypothyroid patients compared with euthyroid ones. After treatment with levothyroxine, antibody level in hypothyroid cases also remained higher than that of euthyroid ones (P<0.001). Anti-TPO antibody level in Hashimoto patients with hypothyroidism is higher than euthyroid ones. After treatment, anti-TPO antibody level decreases in both groups but the decrease is more prominent in euthyroid cases than patients who remain hypothyroid. Regarding these facts, it could be confirmed that anti-TPO antibody measurement (as an important diagnostic and follow-up procedure and for prognosis in Hashimoto) will be useful.