ARUP's Laboratory Test Directory

0070133: Triiodothyronine, Free (Free T3)

Test Mnemonic: FT3
Methodology: Electrochemiluminescent Immunoassay

Performed: Sun-Sat

Reported: Within 24 hours

Specimen Required:  
Collect: One 4 mL SST or PST. Also acceptable: one 3 mL lavender (EDTA) or pink (K2 EDTA).

Transport: 1 mL serum or plasma at 2-8°C. (Min: 0.5 mL) Submit sample in an ARUP Standard Transport Tube.

Pediatric Collection/Transport: 0.3 mL serum or plasma at 2-8°C.

Remarks: Allow serum to clot completely at room temperature.  Separate serum or plasma from cells ASAP.

Unacceptable Conditions: Grossly hemolyzed samples.

Stability: After separation from cells: Ambient: 24 hours; Refrigerated: 1 week; Frozen: 1 month

Reference Interval:
0-6 years: 2.4-4.2 pg/mL
7-17 years: 2.9-5.1 pg/mL
18 years and older: 2.4-4.2 pg/mL

CPT Code(s):
84481