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HelpTest Code T4FT4 T4 (Thyroxine), Total and Free, Serum
Reporting Name
T4 (Thyroxine), Total and FreePerforming Laboratory
Mayo Clinic Laboratories in Rochester
Method Name
Electrochemiluminescence Immunoassay
Specimen Required
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Specimen Type
SerumSpecimen Minimum Volume
0.625 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 7 days | |
| Frozen | 30 days | ||
| Ambient | 72 hours |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | OK |
| Gross icterus | Reject |
Reference Values
T4 (THYROXINE), TOTAL ONLY
0-5 days: 5.0-18.5 mcg/dL
6 days-2 months: 5.4-17.0 mcg/dL
3 -11 months: 5.7-16.0 mcg/dL
1 -5 years: 6.0-14.7 mcg/dL
6 -10 years: 6.0-13.8 mcg/dL
11 -19 years: 5.9-13.2 mcg/dL
 ≥20 years: 4.5-11.7 mcg/dL
T4 (THYROXINE), FREE
0-5 days: 0.9-2.5 ng/dL
6 days-2 months: 0.9-2.2 ng/dL
3-11 months: 0.9-2.0 ng/dL
1-5 years: 1.0-1.8 ng/dL
6-10 years: 1.0-1.7 ng/dL
11-19 years: 1.0-1.6 ng/dL
 ≥20 years: 0.9-1.7 ng/dL
Day(s) Performed
Monday through Sunday
Report Available
Same day/1 to 2 daysTest Classification
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.CPT Code Information
84436
84439
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| T4FT4 | T4 (Thyroxine), Total and Free | 90224-7 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| T4F | T4 (Thyroxine), Free, S | 83122-2 |
| T4CC | T4 (Thyroxine), Total Only, S | 83119-8 |
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| T4F | T4 (Thyroxine), Free, S | No | Yes |
| T4CC | T4 (Thyroxine), Total Only, S | No | Yes |