Test Code FT4 T4 (Thyroxine), Free
Additional Codes
Compendium Code (Iatric): 303.1049
Performing Laboratory
St. Lukes Hospital Laboratory
Methodology
Competitive Chemiluminescent Immunoassay
Specimen Requirements
Do not use samples that have been stored at room temperature for longer than 8 hours.
Tightly cap and refrigerate specimens at 2–8°up to 48 hours.
Draw blood in a serum gel tube(s) preferred. Plasma from lithium heparin is acceptable.
Spin down and send 1 mL of serum (or plasma) refrigerated.
Unspun specimens must be transported at ambient temperature and arrive to the laboratory within one hour of draw.
Reference Values
0.80-1.76 ng/dL
Day(s) Test Set Up
Monday through Sunday
Test Classification and CPT Coding
CPT: 84439
LOINC: 3024-7