Thyroxine, Fr by Eq Dialysis/HPLC-TndmMS
Test Mnemonic
T4HPLC
CPT Codes
- 84439 - QTY (1)
LOINC ®
6892-4
Includes
- Free T4
Performing Laboratory
ARUP
Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 2 mL | Serum | No additive (Red) | Refrigerated | Separate from cells ASAP or within 2 hours of collection and transfer into standard aliquot tube. |
Alternate Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 2 mL | Serum | SST (Gold) | Refrigerated | Separate from gel ASAP or within 2 hours of collection and transfer into standard aliquot tube. |
Minimum Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 0.3 mL |
Stability
| Environmental Condition | Description |
|---|---|
| Ambient | After separation from cells: 4 days |
| Refrigerated | After separation from cells: 2 weeks |
| Frozen | After separation from cells: 1 month |
Days Performed
Sun, Tue, Thu
Turnaround Time
3 - 7 days
Methodology
| Name | Description |
|---|---|
| Equilibrium Dialysis | |
| High Performance Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS) |
Special Info
Plasma specimens will be rejected. This test is New York DOH approved.
Clinical Info
This test is not recommended for routine evaluation of thyroid disorders. Some medications may induce transient changes in FT4 concentrations. This test is not recommended for patients currently on heparin treatment as FT4 concentrations may be falsely elevated.