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UW Health SMPH
American Family Children's Hospital

UW Hospital and Clinics Lab Test Directory

Test Name: T3, Free

Test Code(s): FT3

CPT Code(s): 84481

Methodology: Chemiluminescent Immunoassay

Request Form: UWHC Laboratory Request Form (UWH 1289220, 4004202); Write in test if not on form.

Days Performed: Daily, 24 hours.

Turnaround Time: Stat: 1 hour.
Routine: 4 hours.

Specimen Requirements

Specimen: Blood

Collection Container: Preferred: Green cap with yellow ring (PST)
Also Acceptable: Green top, Red cap with yellow ring (SST), Red top

Collection Volume: Preferred: 2 mL
Pediatrics: 0.4 mL

Sample Analyzed: Plasma or serum

Volume Required: Preferred: 1 mL
Pediatrics: 0.2 mL

Specimen Processing: Centrifuge.  If a complete barrier has not formed, transfer cell-free plasma/serum to plastic vial.  Refrigerate.

Specimen Transport: Transport specimen to UWHC Core Laboratory (B4/220). Transport with coolant pack if coming from outreach location.

Stability: Refrigerated: 7 days
Frozen: okay; avoid repeated freeze/thaw cycles


Reference Interval:
 Age  pg/mL
  0 days - 11 months   2.8-6.5
  1 year - 10 years   2.6-5.2
  11 years - 17 years   2.3-4.8
  18 years and up   2.2-4.0

Free Triiodothyronine  Free T3

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