Phenylalanine, Quantitative, Plasma by HPLC

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PHENYLALANINE, QUANTITATIVE, PLASMA BY HPLC

TURNAROUND TIME:   3 - 4 days
 
PERFORMED :  Monday through Friday
 
TESTING METHODOLOGY:  High Pressure Liquid Chromatography (HPLC)
 
SPECIMEN REQUIREMENTS:
  • Collect: Green (Sodium or Lithium Heparin)
  • Min. Collection: 1.0 mL Whole Blood
  • Transport: Separate plasma from cells ASAP or within 2 hours of collection and freeze immediately.  CRITICAL FROZEN.  Separate specimens must be submitted when multiple tests are ordered to avoid freeze/ thaw cycles.
  • Stability: After separation from cells: Ambient: Unacceptable; Refrigerated: 12 hours;  Frozen: 1 month (Avoid repeated freeze/thaw cycles)
  • Unacceptable Conditions: Specimens at Room Temperature for more than 2 hours; Specimens refrigerated more than 12 hours.
REFERENCE INTERVAL:
 
Normal ranges are based upon literature values and expert opinion.
Phenylalanine
Differential
Acronym
Analyte Cutoff
(µmol/L)
Analyte Ratio Cutoff
Phenylalanine
PKU
Phe > 182
Phe/ Tyr > 2.0
 
INTERPRETATIVE DATA:
 
Clinical correlation is necessary for appropriate interpretation of results.  Additional required information includes age, gender, diet (e.g., TPN therapy), drug therapy, and family history. Clinical information should be included on the Biochemical Genetics Test Requisition Form.
 
Analytic Sensitivity: >99%
 
Test Limitations: Separation of cells from serum and frozen within 2 hours of collection is required for optimal test results.
 
INDICATIONS FOR USE: Intended for the monitoring of phenylketonuria in patients on a metabolic diet.
 
ADDITIONAL RESOURCES:
The American College of Medical Genetics Action Sheets and Algorithms for Newborn Screening: www.acmg.net/resources/policies/ACT/condition-analyte-links.htm
Genetics Home Reference:   http://www.ghr.nlm.nih.gov/gene/PAH
Metabolic and Information Center: www.metagene.de