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Test Code T3UP T3 (Triiodothyronine), Uptake, Serum

Performing Laboratory

Northwell Health Laboratories


Electrochemiluminescence Immunoassay (ECLIA)

Includes calculation of free thyroxine (T4) index when T4 is also ordered.

Reference Values

T3UP:             0.8-1.3  TBI Units

%T3UP:          28-41    %

FTI:                 4.4-11.4 Index

%FTI:              1.4 - 4.8    %

Test Classification and CPT Coding


Specimen Required

Container/Tube: Gold-top tube(s)

Specimen: 1 mL of serum

Transport Temperature: Refrigerate

Stability:  8 Days Room Temperature

                14 Days Refrigerated

               24 Months Frozen

Day(s) and Time(s) Performed

Monday through Sunday, Continuously

Computer Interface Code

PDM #  5300420