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HelpTest Code FFT4F T4, Free, Direct Dialysis
Specimen Required
Patient Preparation:
Fasting: 8-16 hours, preferred but not required
Collection Container/Tube:
Preferred: Red top
Acceptable: Serum gel
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collections Instructions:
1. Centrifuge and aliquot 1 mL of serum into a plastic vial.
2. Send refrigerated.
Method Name
Equilibrium Dialysis, Chromatography/Mass Spectrometry
Reporting Name
T4, Free, Direct DialysisSpecimen Type
SerumSpecimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum | Refrigerated (preferred) | 14 days |
| Frozen | 35 days | |
| Ambient | 4 days |
Reject Due To
| Lipemia | Reject |
| Heparin plasma | Reject |
| EDTA plasma | Reject |
Reference Values
Prematures, 25-30 weeks:
Birth-7 days: 0.5-3.3 ng/dL
Prematures, 31-36 weeks:
Birth-7 days: 1.3-4.7 ng/dL
Cord Blood, >37 weeks: 1.2-2.2 ng/dL
Birth-4 days: 2.2-5.3 ng/dL
2 months to 2 years: 1.2-2.5 ng/dL
3 to 17 years: 1.0-2.4 ng/dL
Adult: 0.9-2.2 ng/dL
Pregnancy:
First Trimester: 0.9-2.0 ng/dL
Second Trimester: 0.8-1.5 ng/dL
Third Trimester: 0.8-1.7 ng/dL
Day(s) Performed
Monday through Saturday
Report Available
4 to 8 daysPerforming Laboratory
Quest Diagnostics Nichols InstituteCPT Code Information
84439
Useful For
Differential diagnosis of euthyroid hyperthyroxinemia from hyperthyroidism or hypothyroidism