Endocrine Abstracts

Introduction: The main objective in the management of primary hypothyroidism is to normalize thyrotropin (TSH) level with Levothyroxine replacement therapy. The optimal dose of Levothyroxine may be affected by several factors such as age, gender, body weight, some medical disorders and drugs intake. The aim of this study was to assess the relationship between thyroid antibody titers and Levothyroxine dose in patients with primary hypothyroidism secondary to Hashimoto thyroiditis.

Patients and methods: In a cross sectional study, we enrolled 40 women with primary hypothyroidism secondary to Hashimoto thyroiditis. All patients were put on Levothyroxine replacement therapy for at least one year. Patients with liver dysfunction, renal failure, malabsorption diseases and pregnancy and those taking drugs affecting lévothyroxine absorption or metabolism were excluded. Anti-thyroid peroxidase antibodies (TPOAb) were measured in all participants.

Results: The study population consisted of 40 patients, all women with a mean age of 53.08±11.46 years. The mean duration of treatment with Levothyroxine was 5.15±4.35 years. TPOAb were positive in all participants. Euthyroidism was achieved in 33 patients (83% of cases). TSH level was 2.66±1.58 μIU/ml in euthyroid group vs 9.72±4.58 μIU/ml in non-euthyroid group (P<0.001). Mean TPOAb levels in euthyroid group and non-euthyroid group were 564.42±349.84 IU/ml and 1533.33±1497.98 IU/ml, respectively (P=0.007). TPOAb titers were positively correlated with Levothyroxine dose (r=0.338, P=0.03). However no correlations were found between Levothyroxine dose and age, body weight, body mass index and the severity of hypothyroidism at the diagnosis.

Conclusion: Our results revealed a positive correlation between TPOAb titers and Levothyroxine dose in patients with primary autoimmune hypothyroidism. Therefore, a higher dose is necessary to achieve euthyroidism in patients with higher TPOAb titers.