Phenylalanine and Tyrosine


Biochemical Genetics Laboratory Phenylalanine and Tyrosine
Phenylalanine and Tyrosine

INDICATIONS FOR TESTING:
Phenylalanine and Tyrosine testing is used for the diagnosis and monitoring of patients with PKU (phenylketonuria) or defects of tyrosine metabolism.

METHODOLOGY:
Analysis is performed by Ion Exchange Chromatography with post column fluorescent detection. Quantitation of phenylalanine and tyrosine is achieved by integrating the area of each peak and comparing to an internal standard. Calibration is routinely performed with reference materials. Retention times are used for identification. Analysis can be performed from blood collected on filter cards as well as traditionally collected plasma, serum and urine.

TURN-AROUND TIME:
Phenylalanine/Tyrosine analysis is completed within a time of 2 working days following specimen receipt. Samples are analyzed daily. One-day turn-around time is offered on all infant-screening follow-up patients.

SPECIMEN REQUIREMENTS:

Filter Cards:

  • 2 - 4 spots on SS 903 filter cards
  • Serum/Plasma/urine: 0.5 mL

Collection Notes:

Filter Cards:
Blood must completely saturate paper within designated circle and at least 0.25 inches in diameter as viewed from both sides. Allow even flow of blood onto card. Do not apply more blood to a previous spot that has been drying over two minutes. Patient name with date/time of collection must be on card.

Shipping and Handling:

Filter Cards:
Mail in security envelope with standard postage to:

All Children's Hospital
Pathology & Lab Medicine
Attn: Phenylalanine Testing
501 6th Avenue South, Dept. 7020
St. Petersburg, FL 33701

(Mailing supplies can be provided upon request)

Serum/plasma/urine:

  • Optimal: Ship frozen with dry ice in an insulated container.
  • Acceptable: Shipped thawed with cool pack in an insulated container.
  • Use overnight delivery if available.

CPT CODE:

  • Phenylalanine: 84030
  • Tyrosine: 84510

FOR MORE INFORMATION, PLEASE CONTACT:
Phone:
(727) 767-8689 (Laboratory)
Fax: (727) 767-8514
E-mail: sbenfor1@jhmi.edu