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Specimen Collection Manual and Test Catalog

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T3, REVERSE, LCMSMS

Geisinger Epic Procedure Code:  LAB3125    Geisinger Epic ID:  17562

SPECIMEN COLLECTION
Specimen type: 

Serum (preferred) or plasma.


Preferred collection container: 
Alternate collection container: 
3 mL lavender-top (K2 EDTA) tube
4 mL green/green-top (sodium heparin) tube
Specimen required: 

0.5 mL aliquot of serum or plasma; minimum 0.3 mL.


Special notes: 

Do not submit gel tube. See Specimen Processing Instructions.



SPECIMEN PROCESSING
Processing instructions: 

Allow to serum to clot. Centrifuge serum or plasma and aliquot. Sample must be removed from gel within 24 hours; do not submit in SST.


Transport temperature: 

Room temperature.


Specimen stability: 

Room Temperature: 7 days. Refrigerated: 7 days. Frozen: 30 days.


Rejection criteria: 

Stability limits exceeded. Serum submitted still in gel tube.



TEST DETAILS
Reference interval: 

8-25 ng/dL


CPT code(s):  84482
Note: The billing party has sole responsibility for CPT coding.  Any questions regarding coding should be directed to the payer being billed.
The CPT codes provided by GML are based on AMA guidelines and are for informational purposes only.

Test includes: 

Reverse T3 (rT3).


Methodology: 
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
Synonyms: 

T3, Triiodothyronine, Reverse; T3R, Quest test code 90963


Clinical significance: 

The assay may be useful in the diagnosis of nonthyroidal illness (NTI). Patients with NTI have low T3 concentrations and increased concentrations of rT3. RT3 may be useful in neonates to distinguish euthyroid sick syndrome from central hypothyroidism.


Review Date:  11/12/2024

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