Thyroid function testing
All serum acquired were immediately tested for T3, FT3, T4, FT4, and TSH levels on the same day using the commercial electrochemiluminescence immunoassay kits (Roche Diagnostics GmbH, Cobas e601 analyzer, Germany). The levels of T3 (reference range, 1.20 - 3.10 nmol/L), FT3 (reference range, 3.10 - 6.80 pmol/L), T4 (reference range, 66.00 - 181.00 nmol/L), FT4 (reference range, 9.87 - 17.26 pmol/L), and TSH (reference range, 0.39 - 5.22 μIU/ml) were determined on the same day.