ARUP's Laboratory Test Directory

Triiodothyronine, Free (Free T3) : 0070133

Mnemonic: FT3

Ordering Recommendation: Not recommended for routine thyroid screening.
Methodology: Quantitative Electrochemiluminescent Immunoassay
Performed: Sun-Sat
Reported: Within 24 hours
Specimen Required: Collect: Serum separator tube or plasma separator tube. Also acceptable: Lavender (EDTA) or pink (K2EDTA).

Specimen Preparation: Allow specimen to clot completely at room temperature. Separate serum or plasma from cells ASAP or within 2 hours of collection. Transfer 1 mL serum or plasma to an ARUP Standard Transport Tube. (Min: 0.5 mL)

Storage/Transport Temperature: Refrigerated.

Unacceptable Conditions: Grossly hemolyzed specimens.

Stability (collection to initiation of testing): After separation from cells: Ambient: 24 hours; Refrigerated: 1 week; Frozen: 1 month
Reference Interval:
 
0-3 days 2.0-7.9 pg/mL
4-30 days 2.0-5.2 pg/mL
1-24 months 1.6-6.4 pg/mL
2-6 years 2.0-6.0 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
Cross References: T3, Free (Triiodothyronine, Free (Free T3))