Thyroxine, Total, serum
Test Code
TT4
Description
Collect
Plain red top or SST tube.
Specimen Preparation
Onsite [NJH]: Transport to lab within 1 hour.
Offsite: Separate serum from cells within 2 hours by centrifuge and aliquot into a labeled polypropylene or similar plastic tube.
Preferred volume: 1 mL serum
Pediatric Collection
Minimum volume: 0.5mL serum
Unacceptable Conditions
Grossly hemolyzed specimens, more than one freeze/thaw cycle.
Storage Transport Temp
Offsite: Send frozen serum Priority Overnight via FedEx and in a well insulated container on dry ice.
Stability
Stability after cell separation:
24 hours at RT (15-25°C)
6 days refrigerated at 2-8°C.
6 days frozen at ≤ -10°C ( avoid multiple freeze thaw cycles)
Performed
Mon & Thurs
Methodology
Chemiluminescent Magnetic Immunoassay (CLIA)
Reported
Results same day if samples are received Mon or Thurs prior to 6PM; 48-72 hours
Department
Core LabSynonyms
TT4 (Thyroxine, total, serum);TT4
Reference Interval
6.1 - 12.2 ug/dL
CPT Code
84436