Sign in →

Test Code T4FT4 T4 (Thyroxine), Total and Free, Serum

Useful For

Assessing thyroid function when thyroid function disorders are suspected

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

Reporting Name

T4 (Thyroxine), Total and Free

Specimen Type

Serum


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 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

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 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test 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

Method Name

Electrochemiluminescence Immunoassay