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HelpTest Code FRT4D T4 (Thyroxine), Free, Dialysis, Serum
Test Down Notes
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Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
SerumOrdering Guidance
The routine free T4 is faster and provides useful information for most patients; order FRT4 / T4 (Thyroxine), Free, Serum.
Necessary Information
Include name and telephone number of contact physician
Specimen Required
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube:
Preferred: Red top
Acceptable: Serum gel
Submission Container/Tube: Plastic vial
Specimen Volume: 2.6 mL
Collection Instructions:
1. Collect specimen immediately before next scheduled dose.
2. Within 2 hours of collection, centrifuge, and aliquot serum into a plastic vial.
Specimen Minimum Volume
1.2 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 28 days | |
| Frozen | 21 days | ||
| Ambient | 7 days |
Reference Values
0.8-2.0 ng/dL
Reference values apply to all ages.
Day(s) Performed
Monday, Wednesday, Thursday
CPT Code Information
84439
Report Available
3 to 8 daysReject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | Reject |
Method Name
Equilibrium Dialysis/Tandem Mass Spectrometry (MS/MS)