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HelpTest Code LAB3371 Phenylalanine, Tyrosine
Additional Codes
Tyrosine can be ordered individually using test code (LAB1103).
Clinical System Name
Phenylalanine, Tyrosine
Synonyms
Phe Tyr
Description
Quantitation of phenylalanine and tyrosine by ion exchange chromatography for nutritional monitoring. Recommended for patients with unknown diganosis of PKU or Tyrosinemia.
Sample Requirements
Specimen: Whole Blood, Capillary Blood
Container(s): Dark Green/Sodium Heparin, Lt. Green/Lithium Heparin, Dried Blood Spot (DBS)
Preferred Vol: 1 mL, 3 full circles DBS card
Minimum Vol: 0.5 mL, or 1 full circle DBS card
Note: Serum is acceptable but not preferred.
Processing Instructions
Reject due to:
Spin:Y
Aliquot:Y
Temp:-20 C
Storage location: -20C BCG Box, Spot cards stored in RT BCG box
Off-site collection: Spin and separate serum/plasma within 1 hr of collection. Freeze plasma/serum and ship frozen.
Stability
| Temperature | Time |
|---|---|
| Room temp (whole blood) | 1h |
| Room temp (serum/plasma) | 2h |
| Refrigerated (serum/plasma) | 24h |
| Frozen (Plasma/Serum) | 1m |
| Dried blood spot (Room temp, Refrigerated, Frozen) | 1m |
Patients receiving enzyme replacement therapy shold have plasma/serum frozen within 1 hour of collection to minimize therapeutic interference.
Availability
| STAT | Performed | TAT |
|---|---|---|
| N | M-F | 3 days |
Contact the Biochemical Genetics Lab for requests outside of stated availability (206)987-2216.
Performing Laboratory
Seattle Children's Laboratory
Department
Department: Biochemical Genetics
Phone Number: 206-987-2216
Methodology
Method: Ion exchange chromatography with post column derivatization
Analytical Volume: 0.1 mL
Limitations:
CPT Codes
Phe 84030
Tyr 84510
Requisition
Biochemical Genetics Requisition
On the requisition include clinical information needed for appropriate interpretation. (Age, gender, diet (e.g. TPN therapy), drug therapy and family history)
Reference Ranges
|
(mg/dL) |
|
| Phenylalanine | 0.5 - 1.5 |
| Tyrosine | 0.6 - 2.6 |
Ranges updated 9/1/26.