Test Code Free T4 T4 (Thyroxine), Free, Plasma or Serum
Performing Laboratory
NRL-Chemistry
Methodology
Immunoenzymatic
Specimen Requirements
Submit only 1 of the following specimens:
Preferred:
Specimen Type: Plasma
Container/Tube: Light-green top (lithium heparin)
Specimen Volume: 2 mL
Collection Instructions:
1. Spin down within 45 minutes of draw.
2. Label specimen as plasma.
Alternate (Non-Hospital Patient):
Specimen Type: Serum
Container/Tube: Gold top, serum gel
Specimen Volume: 2 mL
Collection Instructions:
1. Spin down unopened (vacuum intact) tube within 45 minutes of draw.
2. Label specimen as serum.
Reference Values
≥1 month: 0.61-1.12 ng/dL
Day(s) Test Set Up
Monday through Sunday
Turnaround Time:
Routine-shift
Specimen Transport Temperature
Refrigerate
Test Classification and CPT Coding
84439
Stability
7 Days