Sign in →

Phenylalanine and Tyrosine, Plasma

Important Note

While a microtainer is an optional tube type in rare circumstances, it is not recommended.

Additional Codes

Primary ID

 Epic Code Mayo Test ID

PHETYR

 LAB2494 PKU

 

Reporting Name

Phenylalanine and Tyrosine, P

Useful For

Monitoring effectiveness of dietary therapy in patients with hyperphenylalaninemia

Method Name

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

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Plasma
University of Vermont Medical Center Laboratory Test Catalog Note:

While a microtainer is an optional tube type in rare circumstances, it is not recommended.


Necessary Information


1. Patient's age is required.

2. Include family history, clinical condition (asymptomatic or acute episode), diet, and drug therapy information.



Specimen Required


Patient Preparation: Patient should fast overnight (8-12 hour fast); infants should have specimen collected before next feeding (4 hour fast)

Collection Container/Tube:

Preferred: Green top (Sodium heparin)

Acceptable: Green top (Lithium heparin), lavender top (EDTA)

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL

Collection Instructions:

1. Centrifuge and aliquot plasma into a plastic vial.

2. Send plasma frozen.


Specimen Minimum Volume

0.1 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Plasma Frozen (preferred) 14 days
  Refrigerated  14 days

Reject Due To

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK

Reference Values

PHENYLALANINE

Premature: 98-213 nmol/mL

0-31 days: 38-137 nmol/mL

1-24 months: 31-75 nmol/mL

2-18 years: 26-91 nmol/mL

≥19 years: 35-85 nmol/mL

 

Conversion Formulas:

Result in mg/dL x 60.5=result in nmol/mL

Result in nmol/mL x 0.0165=result in mg/dL

 

TYROSINE

Premature: 147-420 nmol/mL

0-31 days: 55-147 nmol/mL

1-24 months: 22-108 nmol/mL

2-18 years: 24-115 nmol/mL

≥19 years: 34-112 nmol/mL

 

Conversion Formulas:

Result in mg/dL x 55.2=result in nmol/mL

Result in nmol/mL x 0.0181=result in mg/dL

Day(s) Performed

Monday through Friday

CPT Code Information

84030 Phenylalanine

84510 Tyrosine

82542 (if appropriate for government payers)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
PKU Phenylalanine and Tyrosine, P 101402-6

 

Result ID Test Result Name Result LOINC Value
8380 Phenylalanine, P 14875-9
8627 Tyrosine, P 20660-7

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

Report Available

2 to 4 days

Specimen Retention Time

2 weeks

NY State Approved

Yes