tokens: METHODS : Thyroid status was measured at baseline ( 1990-93 ) , through assessment of serum antibodies to thyroid peroxidase ( TPO-Abs , positive : > 10 IU / ml ) , serum TSH levels , and when TSH was abnormal ( < 0.4 or > 4.0 mU / l ) , serum thyroxin levels ( T4 ) .
folded_tokens: method : thyroid status be measure at baseline ( 1990-93 ) , through assessment of serum antibody to thyroid peroxidase ( tpo-ab , positive : > 10 iu / ml ) , serum tsh level , and when tsh be abnormal ( < 0.4 or > 4.0 mu / l ) , serum thyroxin level ( t4 ) .