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8380M
PHENYLALANINE AND TYROSINE, PLASMA

Test Code 8380M 
Test PHENYLALANINE AND TYROSINE, PLASMA 
Methodology Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) 
Description Evaluation of patients with hyperphenylalaninemia. Monitoring effectiveness of dietary therapy in patients with hyperphenylalaninemia. 
Specimen Draw blood in a green-top (heparin) tube from a fasting patient (a fast of 4 hours or more in infants). (THROMBIN-ACTIVATED TUBE IS NOT ACCEPTABLE.) Spin down promptly and send 0.5 mL (minimum: 0.25 mL) of heparinized plasma FROZEN in plastic vial.

NOTE:
1. Include family history, clinical condition (asymptomatic or acute episode), diet, and drug therapy information.
2. PATIENT'S AGE IS REQUIRED ON REQUEST FORM FOR
PROCESSING. 

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
> or =19 years: 35-85 nmol/mL

Conversion Formulas:
Result in mg/dL x 60.6=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
> or =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
See "Inborn Errors of Amino Acid Metabolism" in Special Instructions. 

Analytic Time 2 Days 
Day(s) Test Set Up Monday through Friday 
CPT Code(s) 84030  Phenylalanine
84510  Tyrosine

Special Instructions