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Test Code FREE T3 Free Triiodothyronine

Clinical System Name

Free Triiodothyronine


Free T3

Sample Requirements

Specimen:Whole blood

Container(s): Gold SST Microtainer, Gold SST

Preferred Vol: 1 mL

Minimum Vol: 0.5 mL




Processing Instructions

Reject due to:

Spin: Y

Aliquot: Y

Temp: 2 - 8 C

Storage location: CPA Refrigerator, FrigD rack. Serum should be removed from separator for storage.


Off-site collection: Spin blood and aliquot serum in plastic aliquot tube. Send refrigerated.


Specimen Type Temperature Time
serum Room temp 2 h
  Refrigerated 7 d
  Frozen 4 w



STAT Performed TAT
N M - Sa 1 - 3 d


Performing Laboratory

Seattle Children's Laboratory    



Department:  Chemistry

Location: Chem West

Phone Number: (206) 987-2617



Reference Range


Age pg/mL
cord blood 2.69-2.92
0-24 hr 7.76-9.71
1 day 10.2-10.7
2 days 5.95-7.22
3 -30 days 3.76-5.74
1 mo-18 yr 3.65-6.85
Adult 2.77-5.27



Method:Competitive Immunoassay with chemiluminescent detection by Vitros 3600.

Analytical Volume: 0.15 mL

Limitations:Bilirubin 20 mg/dL causes a positive interference of 15-20%.  Bilirubin less than 9.4 mg/dL is ok.

CPT Codes