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Test Code PKU Phenylalanine and Tyrosine, Plasma

Reporting Name

Phenylalanine and Tyrosine, P

Useful For

Monitoring effectiveness of dietary therapy in patients with hyperphenylalaninemia

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Plasma


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: Fasting (4 hours or more in infants)

Collection Container/Tube:

Preferred: Green top (sodium heparin)

Acceptable: Lavender top (EDTA)

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL


Specimen Minimum Volume

0.1 mL

Specimen Stability Information

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

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 60.6=result in nmol/mL

 

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 55.6=result in nmol/mL

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

Day(s) and Time(s) Performed

Monday through Friday; 1 p.m.

Test Classification

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

CPT Code Information

84030-Phenylalanine

84510-Tyrosine

LOINC Code Information

Test ID Test Order Name Order LOINC Value
PKU Phenylalanine and Tyrosine, P In Process

 

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

Reject Due To

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK

Method Name

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

Forms

If not ordering electronically, complete, print, and send an Inborn Errors of Metabolism Test Request (T798) with the specimen.