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Test Code T3UP T3 (Triiodothyronine), Uptake

Additional Codes

EPIC:  LAB2556

Methodology

Chemiluminescent Immunoassay


Used to determine total thyroxine (T4) binding capacity and used in conjunction with total T4 to yield the free thyroxine index, an indirect indicator of thyroid function.

Performing Laboratory

St. Joseph Hospital

Specimen Requirements

Preferred:  Plasma

Draw blood in a light green-top (PST - lithium heparin gel) tube(s). (Hemolyzed specimen is not acceptable.) Spin down, separate plasma from cells within 2 hours of collection, and send 1 mL of lithium heparin plasma refrigerated.

Note:  Label specimen as “plasma”. 

Acceptable:  Serum

Draw blood in a plain, red-top tube(s) or SST- serum gel tube(s). (Hemolyzed specimen is not acceptable.) Centrifuge, separate serum from cells within 2 hours of collection, and send 1 mL of serum refrigerated.

Note:  Label specimen as “serum”

Reference Values

Males:  33-40%

Females:  30-39%

Day(s) Test Set Up

Monday through Sunday

Test Classification and CPT Coding

84479