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Specimen Collection Manual and Test Catalog

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T4, FREE

Geisinger Epic Procedure Code:  LAB3128    Geisinger Epic ID:  7018

SPECIMEN COLLECTION
Specimen type: 

Plasma or Serum


Preferred collection container: 
Specimen required: 

2 mL of serum or plasma; minimum 0.5 mL.



SPECIMEN PROCESSING
Processing instructions: 

Allow serum to clot. Centrifuge to separate serum or plasma within 2 hours of collection.


Transport temperature: 

Refrigerated (preferred) or frozen.


Specimen stability: 

Refrigerated: 7 days. Frozen: 1 month.


Rejection criteria: 

Stability limits exceeded.



TEST DETAILS
Reference interval: 

0.9-1.7 ng/dL


CPT code(s):  84439
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: 

Free T4.


Methodology: 
Electrochemiluminescence Immunoassay
Synonyms: 

Free thyroxine, FREET4


Clinical significance: 

For the diagnosis of hypothyroidism and hyperthyroidism.


Doctoral Director(s): 
Hoi-Ying Elsie Yu, PhD, DABCC, FADLM
Sheng-Ying (Margaret) Lo, PhD, DABCC
Review Date:  12/27/2024

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