Referred Tests
| Web: | mayocliniclabs.com |
|---|---|
| Email: | mcl@mayo.edu |
| Telephone: | 800-533-1710 |
| International: | +1 855-379-3115 |
| Values are valid only on day of printing. | |
Test ID: FRT4
T4 (Thyroxine), Free, Serum
Testing Algorithm 
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
See Thyroid Function Ordering Algorithm in Special Instructions.
Specimen Type Describes the specimen type validated for testing
Serum
Specimen Required Defines the optimal specimen required to perform the test and the preferred volume to complete testing
Patient Preparation: For 12 hours before specimen collection do not take multivitamins or dietary supplements containing biotin (vitamin B7), which is commonly found in hair, skin, and nail supplements and multivitamins.
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Special Instructions Library of PDFs including pertinent information and forms related to the test
Specimen Minimum Volume Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory
0.5 mL
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Gross hemolysis | OK |
| Gross lipemia | OK |
| Gross icterus | OK |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 14 days | |
| Frozen | 30 days | ||
| Ambient | 72 hours |