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Specimen Collection Manual and Test Catalog

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TRYPTOPHAN

Geisinger Epic Procedure Code:  LAB1360    Geisinger Epic ID:  53358

SPECIMEN COLLECTION
Specimen type: 

Plasma


Preferred collection container: 
Alternate collection container: 
3 mL lavender-top (K2 EDTA) tube
Specimen required: 

2 mL plasma; minimum 0.25 mL.


Special notes: 

Date of birth must be provided.


Patient preparation: 

Collect plasma specimens after an overnight fast (or at least 4 hours after a meal). Non-fasting samples are acceptable for pediatric patients.



SPECIMEN PROCESSING
Processing instructions: 

Plasma should be separated from cells as soon as possible after collection. Freeze plasma below -20ºC and ship frozen.


Transport temperature: 

Frozen.


Specimen stability: 

Room temperature: Unacceptable. Refrigerated: 7 days. Frozen: 30 days.


Rejection criteria: 

Gross hemolysis.



TEST DETAILS
Additional information: 

This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by the U.S. Food and Drug Administration. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.


CPT code(s):  82131
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.

Synonyms: 

Quest test code 959


Clinical significance: 

Tryptophanuria is a rare autosomal recessive disease associated with mental retardation, neuropsychiatric dysfunction, and photosensitive skin rash.


Review Date:  12/11/2024

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