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Test Code FT4 Free Thyroxine

Aliases

T4 Free

Patient Preparation

No special patient preparation required

Collection Method

Venous collection

Minimum Volume

  • Adults: 0.8 mL
  • Pediatric: 0.6 mL

Container

Lt Green / Plasma Separator / Lithium Heparin

Preferred Specimen

Light Green Top (lithium heparin) plasma

Acceptable Specimens

Serum:

  • Gold Top SST
  •  
  • Red Top


Plasma:

 

  • Light Geen Top (lithium heparin)
  • Purple or Pink Top (K2/K3 EDTA)

 

Reference or Target Ranges

0.9 – 1.8 ng/dL

Reportable Units

ng/dL

Critical Value

Not defined for this assay

Reasons for Rejection

 


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Hemolysis Threshold 250 mg/dL
Icterus Threshold 20 mg/dL
Lipemia Threshold 1000 mg/dL
Other QNS, contaminated, improperly Labeled, improper specimen type

Specimen Stability

 


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Ambient 5 days
Refrigerated (4°C to 8°C) 7 days
Frozen(-40°C to 0°C) 30 days

Performance Information

 


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Days and Time Performed 24/7
Expected Turn Around Time Routine: 4 hours
Stat Availability No
Performing Bench UH Chemistry
Methodology/Method Description Siemens Atellica - Immunoassay

CPT Codes

84439