Phenylalanine and Tyrosine

CPT Code(s):

  • Phenylalanine Only: 84030
  • Tyrosine Only: 84510
  • Phenylalanine and Tyrosine: 82136

Specimen Requirements:

Type: Dried blood spot

Special Instructions: Allow blood to dry completely before placing the specimen in a biohazard bag. Specimens sent through the mail do not require a biohazard bag.


  • Newborn screening card or protein saver card
Sample Volume: 1 circle
Minimum Volume: 1/4 of 1 circle
Storage: Ambient
Stability (collection to time of analysis):

  • Ambient: Stable
  • Refrigerated: Stable
  • Frozen: Stable
Rejection Criteria: Unidentified, diluted or contaminated, unsaturated


This test is used to monitor therapy in phenylketonuria and tyrosinema. It can also be used to evaluate previous phenylalanine and tyrosine elevations.


Liquid chromatography/Tandem mass spectrometry (LC-MS/MS)


Within 3 days