T3 Uptake
0070135
Ordering Recommendation
Not recommended for routine thyroid screening.
Mnemonic
T3 UP
Methodology
Quantitative Electrochemiluminescent Immunoassay
Performed
Sun-Sat
Reported
Within 24 hours  
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
Specimen Required
Patient Preparation
  
Collect
Serum separator tube. Also acceptable: Plasma separator tube, lavender (EDTA), pink (K2EDTA), or green (sodium or lithium heparin).  
Specimen Preparation
Allow serum to clot completely at room temperature. Separate serum or plasma from cells ASAP or within 2 hours of collection. Transfer 1 mL serum or plasma to an ARUP Standard Transport Tube. (Min: 0.5 mL)  
Storage/Transport Temperature
Refrigerated.  
Unacceptable Conditions
Grossly hemolyzed specimens.  
Remarks
  
Stability
After separation of cells: Ambient: 24 hours; Refrigerated: 8 days; Frozen: 3 months  
Reference Interval
28-41% uptake  
Interpretive Data
Thyroxine, Free (Free T4) (0070138) is the preferred test alternative for T3 uptake and Free Thyroxine Index tests.  
Note
T3 uptake is of little clinical value alone; it is used to determine the Free Thyroxine Index.
CPT Code(s)
84479
Components
Component Test Code*Component Chart Name
0070135T3 Uptake
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
Aliases
  • T-Uptake
  • T3 Uptake, S
  • T3U, Serum
  • Triiodothyronine Uptake, Serum