Thyroid Function Tests

Normal Laboratory Values

Test Abbreviation Typical Ranges
Serum thyroxine T4 4.6-12 ug/dl
Free thyroxine fraction FT4F 0.03-0.005%
Free Thyroxine  FT4 0.7-1.9 ng/dl
Thyroid hormone binding ratio  THBR 0.9-1.1
Free Thyroxine index FT4I 4-11
Serum Triiodothyronine T3 80-180 ng/dl
Free Triiodothyronine l FT3 230-619 pg/d
Free T3 Index FT3I 80-180
Radioactive iodine uptake RAIU 10-30%
Serum thyrotropin TSH 0.5-6 uU/ml
Thyroxine-binding globulin TBG 12-20 ug/dl T4 +1.8 ugm
TRH stimulation test Peak TSH 9-30 uIU/ml at 20-30 min
Serum thyroglobulin l Tg 0-30 ng/m
Thyroid microsomal antibody titer   TMAb Varies with method
Thyroglobulin antibody titer TgAb  Varies with method