Laboratory tests
The laboratory reference ranges of thyroid hormones were: TSH: 0.27-4.20
mU/L, T4: 66.00-181.00 nmol/L, free T4: 12.00-22.00 pmol/L, T3:
1.30-3.10 nmol/L, FT3: 3.10-6.80 pmol/L. Standardized criteria of
thyroid function were based on the laboratory reference ranges, as
follows: normal thyroid function: 0.27≤TSH≤4.2 mU/L and 12.00≤free
T4≤22.00 pmol/L. Serum samples were collected between 6:00 and 8:00 AM
following an overnight fasting. The tests were completed on the same day
at the hospital laboratory. Chemiluminescence procedures (Cobas E610 or
411, Roche, Basel, Switzerland) were employed to determine the thyroid
hormones by using Elecsys (TSH, T4, free T4, T3, FT3) kits (Roche
Diagnostics Shanghai Ltd, China).