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HelpTest Code FRT4D T4 (Thyroxine), Free, Dialysis, Serum
Test Down Notes
This test is temporarily unavailable. For additional details see test announcement here.
Ordering 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.
CMH COLLECTION: 3 mL in red gel vacutainer
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 |
Useful For
Determining thyroid status of sick, hospitalized patients
Determining thyroid status of patients in whom abnormal binding proteins have been identified
Possibly useful in pediatric patients
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | Reject |
Day(s) Performed
Monday, Wednesday, Thursday
Report Available
3 to 8 daysReporting Name
T4 (Thyroxine), Free by Dialysis, SReference Values
0.8-2.0 ng/dL
Reference values apply to all ages.
Method Name
Equilibrium Dialysis/Tandem Mass Spectrometry (MS/MS)
Performing Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
84439