Phenylalanine and Tyrosine
Also known as: PHE/TYR
Use
This test is used for monitoring patients with an established diagnosis of phenylketonuria (PKU). Phenylketonuria is a metabolic disorder characterized by the deficiency of the enzyme phenylalanine hydroxylase, leading to elevated levels of phenylalanine in the blood. Monitoring the levels of phenylalanine and tyrosine is critical for the management and dietary control in these patients to prevent neurological damage. The test provides quantitative measurement of these amino acids in plasma, aiding in the assessment of dietary compliance and treatment efficacy.
Special Instructions
The test is designed specifically to monitor treatment and compliance in PKU patients. It requires careful specimen handling and processing as hemolyzed specimens are unacceptable, and immediate freezing is necessary after separation from cells.
Limitations
This test has not been cleared or approved by the US Food and Drug Administration, and its performance characteristics were determined by ARUP Laboratories. It is a Laboratory Developed Test (LDT) performed under CLIA certification standards for clinical purposes. The test may not be suitable for initial diagnosis, as it is intended for monitoring purposes in diagnosed PKU patients. Additionally, improper specimen handling, such as failure to freeze, could affect results.
New York Approved
Methodology
Mass Spectrometry
Biomarkers
LOINC Codes
- 14875-9
- 20660-7
Result Turnaround Time
2-5 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
0.5 mL
Minimum Volume
0.25 mL
Container
ARUP Standard Transport Tube
Collection Instructions
Transfer 0.5 mL plasma to an ARUP Standard Transport Tube.
Storage Instructions
Frozen after separation from cells.
Causes for Rejection
Hemolyzed specimens.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | Unacceptable |
| Refrigerated | 24 hours |
| Frozen | 1 month |