Phenylalanine

Test Code

4347

Quest Code

37356

Alias/See Also

Quest 37356; Sunquest: PNAL

CPT Codes
84030

Preferred Specimen

0.4 mL plasma collected in a sodium heparin (green-top) tube

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.

Minimum Volume

0.2 mL

Other Acceptable Specimens

Plasma collected in: EDTA (lavender-top) tube or lithium heparin (green-top) tube

Instructions

Separate plasma from cells as soon as possible and freeze below -20° C

Transport Container

Transport tube

Transport Temperature

Frozen

Specimen Stability

Room temperature: Unacceptable
Refrigerated: 7 days
Frozen: 28 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Received room temperature

Methodology
Chromatography/Mass Spectrometry

FDA Status
This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by FDA. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.

Setup Schedule

Tues, Thurs

Report Available

3-8 days

Limitations

If non-PKU types of hyperphenylalanemia are suspected, additional testing for tetraahydrobiopterin pathway enzyme defects should be performed.

Reference Range

≤30 days	30-79 umol/L
31 days-23 months	31-92 umol/L
2-17 years	38-86 umol/L
≥18 years	40-74 umol/L

Performing Laboratory

Quest Diagnostics Nichols Institute-San Juan Capistrano, CA

33608 Ortega Highway

San Juan Capistrano, CA 92675-2042

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.