ARUP's Laboratory Test Directory

Thyroxine, Free (Free T4) : 0070138

Mnemonic: FT4

Methodology: Electrochemiluminescent Immunoassay
Performed: Sun-Sat
Reported: Within 24 hours
Specimen Required: Collect:  One 4 mL serum separator tube or plasma separator tube. Also acceptable: green (sodium or lithium heparin) or lavender (EDTA).

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

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

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:
0-30 days:  0.8-2.2 ng/dL
1-6 months:  0.8-1.8 ng/dL
7-11 months:  0.8-1.6 ng/dL
1-6 years:  0.9-1.4 ng/dL
7-11 years: 0.9-1.6 ng/dL
12-17 years: 0.9-1.5 ng/dL
18 years and older:  0.8-1.7 ng/dL
CPT Code(s): 84439
Cross References: T4, Free
 
 

 

 

 
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