ARUP's Laboratory Test Directory

Thyroxine, Free (Free T4) : 0070138

Mnemonic: FT4

Methodology: Quantitative Electrochemiluminescent Immunoassay
Performed: Sun-Sat
Reported: Within 24 hours
Specimen Required: Collect: Serum separator tube or plasma separator tube. Also acceptable: Green (sodium or lithium heparin) or lavender (EDTA).

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 of cells: Ambient: 24 hours; Refrigerated: 1 week; Frozen: 1 month
Reference Interval:
Effective May 16, 2011
 
Free Thyroxine, ng/dL
0-3 days 0.7-2.7 ng/dL
4-30 days 0.8-3.1 ng/dL
1-23 months 0.5-2.3 ng/dL
2-6 years 0.9-1.8 ng/dL
7-11 years 0.9-1.7 ng/dL
12-19 years 0.9-1.6 ng/dL
20 years and older 0.8-1.7 ng/dL
Pregnancy, 1st Trimester 0.9-1.4 ng/dL
Pregnancy, 2nd Trimester 0.7-1.3 ng/dL

CPT Code(s): 84439
Cross References: T4, Free (Thyroxine, Free (Free T4))
 
 

 

 

 
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