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Phenylalanine/Tyrosine (DBS)

Alternate test name

PHE/TYR. blood spot

Lab area
Clinical Biochemistry - Metabolic Diseases
Method and equipment
Measurement by Liquid Chromatography with Tandem Mass Spectrometry (LC-MS/MS)
Expected turn-around time
7 days
Specimen type

Dried Blood spot

Specimen requirements

Saturated filter paper circle. Recommend 2 full circles on a Specimen Collection Card.


Storage and transportation

Allow sample to completely air dry before shipping at room temperature.

Special requirements
  • Circle on DBS card should be fully saturated front to back with blood to be acceptable
  • Follow-up for diagnosed PKU patients
  • Not for newborn screening
Shipping information
The Hospital for Sick Children
Rapid Response Laboratory
555 University Avenue, Room 3642
Toronto, ON
M5G 1X8
Phone: 416-813-7200
Toll Free: 1-855-381-3212
Hours: 7 days/week, 24 hours/day
Background and clinical significance

Phenylalanine and tyrosine are proteinogenic amino acids that when elevated are consistent with PKU related disorders and tyrosinemia (Type I, II and III). Monitoring of blood concentration is important for the effective management of these metabolic disorders. Dried blood spots provide an effective mechanism for sample transport allowing collections to occur outside of a clinical setting.

Disease condition
  • Phenylketonuria
  • PKU
  • PKU related disorders
  • Tyrosinemia
  • Alternate Name/ Synonym  PHE/TYR (filter paper)
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