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Test Code Lab5777 Phenylalanine/Tyrosine, Quantitative, Blood

Performing Laboratory

St. Louis Children's Hospital

Last Reviewed

November 2024

Lab Dept

Core Lab

Specimen Requirements

Specimen Type: Blood

Container/Tube

Preferred: Mint green-top (lithium heparin) Vacutainer®

Acceptable: green SAMPLETTE™/MICROTAINER®; Plain, Red-top Vacutainer ®; or Gold/Red SST gel Vacutainer®

Collection Volume: 2.0 mL (minimum 0.5 mL)

Patient Preparation: None

Sample Rejection: Mislabeled or unlabeled specimens.

Special Instructions: Send to lab promptly.

Interpretive

Reference Range:

PHENYLALANINE

<1 month: 30-120 micmol/L

≥1 month: 30-90 micmol/L

TYROSINE
<1 month: 30-300 micmol/L

1 mo - 1 year: 25-150 micmol/L

≥1 year: 25-100 micmol/L

 

Critical Values: None established

Limitations: NA

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

Test Classification: This test was developed and its performance characteristics determined by St. Louis Children's Hospital Clinical Laboratory. It has not been cleared or approved by the U.S. Food and Drug Administration.

Additional Information

For SLCH Laboratory use only

Lab Processing instructions: Centrifuge specimen to separate and aliquot sample into a plastic conical tube (label as serum if collected in red top or gold/red tube). Place aliquot tube in freezer. (see note below)

Processed Volume: 0.3 mL plasma/serum

Analyte Stability:
Ambient (whole blood or processed): 5 days

PROCESSED

Refrigerated: 1 week

Frozen: Indefinitely

Notes: Specimens coming from outside facilities that are in aliquot containers should be kept in original container sent when given to Met. Genetics lab (put in freezer).

Logistics

Test Availability: Daily
Days set up: Monday-Friday

Cut-off time: Varies; batched once per day in a.m.

Turnaround Time: 24-72 hours

Lab Testing Section: Metabolic Genetics

General Information

EPIC order name: Phenylalanine/Tyrosine
Cerner order name: Phenyl/Tyrosine

CPT Codes:
84030 - Phenylalanine

84510 - Tyrosine

LOINC Value:
Phenylalanine: 14875-9

Tyrosine: 20660-7

Synonyms:

Barnes-Jewish Hospital Additional Information:

 

For BJH Laboratory Use Only
Laboratory Processing Instructions:BJH Core Lab will forward to the performing laboratory. Send specimen to SLCH Core Laboratory for testing.