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HelpTest Code T4 T4 (Thyroxine), Total, Plasma or Serum
Performing Laboratory
North Ottawa Community Hospital
Specimen Requirements
Submit only 1 of the following specimens:
Preferred:
Specimen Type: Plasma
Container/Tube: Mint-green top (lithium heparin gel)
Specimen Volume: 1 mL
Collection Instruction:
1. Label specimen as plasma.
2. Avoid hemolysis and lipemia.
Acceptable:
Specimen Type: Serum
Container/Tube: Serum gel or red top
Specimen Volume: 1 mL
Collection Instruction:
1. Label specimen as serum.
2. Avoid hemolysis and lipemia.
Reference Values
4.7-13.3 µg/dL
Day(s) Test Set Up
Monday through Sunday
Methodology
Competitive Immunoassay
Specimen Transport Temperature
Ambient
Test Classification and CPT Coding
84436
Specimen Storage and Stability
| Specimen Type | Temperature | Time |
| Serum/Plasma | Room Temp | < 4 hours |
| Refrigerated (primary) | <5 days | |
| Frozen | <4 weeks |