Phenylalanine

Last Modified: 10/26/2018 12:34:01 PM


Patient Preparation: Collect specimen after an overnight fast (or at least 4 hours after a meal) if possible. 

Non-fasting samples are acceptable for pediatric patients.
Specimen Requirements: 0.4 mL Plasma from a Green Top Tube - Na Heparin in a Plastic Vial
Collection Instructions: Separate serum as soon as possible and freeze at below -20° C
Minimum Volume: 0.2 mL Plasma
Transport & Storage: Temperature/Stability: 7 days Refrigerated
30 days Frozen (transport)
Rejection Criteria: CSF, Ambient,
Reference Range:
0-30 Days  30-79 µmol/L
31 Days-23 Months  31-92 µmol/L
2-17 Years 38-86 µmol/L
≥18 Years 40-74 µmol/L
To convert µmol/L to mg/dL, multiply the result in µmol/L by 0.0165.
Test Comments: Limitations: If non-PKU types of hyperphenylalanemia are suspected, additional testing for tetraahydrobiopterin pathway enzyme defects should be performed.
Methodology: High Performance Liquid Chromatography (HPLC)
Clinical Significance:

Abnormalities in phenylalanine metabolism are autosomal recessive disorders that occur in 1 in 10,000 births. The most common form is phenylketonuria. Heterozygotes can have transient cognitive impairment with large phenylalanine loads.
Custom Panel: No

PRODUCTION SCHEDULE

Turn Around Time: 5 to 6 days
Days Performed: Tuesday, Thursday
Sites Performed: Quest - Chantilly to San Juan Capistrano
PHL Test Code: MSOT
EPIC Test Code:
Send Out Test Code: 37356
Alternate Test Names: Adult PKU; Phenylalanine Plasma
CPT Coding: 84030

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