ProPath Test Menu


T4, Free


TEST DIRECTORY
Test Name
T4, Free
Alternate Names
FT4
Test Code
FT4
SPECIMEN REQUIREMENTS
Specimen Requirements
Minimum of 2.0 mL serum; alternately 2.0 mL serum from Red Top tube
Supplies for Submission
SST/Gold Top (1); alternately Red Top (1)
Specimen Collection

For patients receiving therapy with high biotin doses (> 5 mg/day), wait for at least 8 hours following the last biotin administration before collecting samples.

  1. Label serum separator tube (SST) with two identifiers. Acceptable identifiers include patient’s name, date of birth, social security number, requisition number, and medical record number.
  2. Allow SST contents to clot in an upright position for at least 30 minutes (60 minutes for Red Top tube).
    • SST specimen - centrifuge within 2 hours of collection and refrigerate.
    • Red Top specimen - centrifuge within 2 hours of collection, transfer serum to a plastic transport tube labelled appropriately and as Red Top serum, and refrigerate.
Storage Requirements
Refrigerated.
Specimens are stable if if stored at room temperature for 7 days, refrigerated for 7 days, or frozen for 30 days.
GENERAL AND TECHNICAL INFORMATION
Turn Around Time
1 day
Limitations
If the sample contains a biotin concentration of > 10 ng/mL, there is the potential of biotin interference effects, and hence, falsely elevated results.
CPT Code
84439