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T4, Total

Source Blood
Mnemonic T4
If only T4 is indicated on the requisition, order Free T4 (FT4). Total T4 (T4) should be ordered ONLY if requisition clearly indicates Total T4.
Specimen Requirements 1 x 3.5 mL gold top SST tube 
Specimen Handling
Additional Information Note to ordering physician: Total thyroxine (T4) is intended to be used for monitoring thyroid status in pregnancy after 12 weeks gestation. Otherwise, order Free T4.
Testing Location Immunochemistry
Testing Frequency Daily
 
Alternate Name(s) Total T4; T4N; Thyroxine, Total
Reference Interval
 0-150 years male and female  59-154 nmol/L
 Pregnancy  85-190 nmol/L