TPO and thyroid gland disorder: TSH: thyroid-stimulating hormone serum levels, fT4: free thyroxine serum levels, fT3: free triiodothyronine serum levels, TRAb: TSH receptor antibodies serum levels, TPOAb: thyroid peroxidase antibodies serum levels, BMI: body mass index, GD: Graves’ disease, ATD: anti-thyroid drug