TEST CATALOG ORDERING & RESULTS SPECIMEN HANDLING CUSTOMER SERVICE EDUCATION & INSIGHTS
Test Catalog

Test ID: T4    
T4 (Thyroxine), Total Only, 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

Advisory Information

This test cannot be used in patients receiving treatment with lipid-lowering agents containing dextrothyroxine (D-T4) unless therapy is discontinued for 4 to 6 weeks to allow the physiological state to become reestablished prior to testing.

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

0.75 mL

Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis Reject
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 TypeTemperatureTimeSpecial Container
SerumRefrigerated (preferred)7 days
 Frozen 30 days