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Test Code Phenylbut Phenylbutyrate Metabolite Analysis

Additional Codes

U Phenylb

Clinical System Name

Phenylbutyrate Metabolite Analysis


This assay measures the levels of phenylacetylglutamine (PAG) and its upstream metabolites phenylbutyrate and phenylacetate in plasma.

Sample Requirements

Specimen: Whole Blood

Container(s): Dark Green/Sodium Heparin

Preferred Vol: 4 mL

Minimum Vol: 2 mL



Processing Instructions

Reject due to:

Spin: Y

Aliquot: Y

Temp: -20 C

Storage Location: CPA -20 freezer, Send Outs rack.


Off-site collection: Spin and aliquot specimen as soon as possible. Send 1-2 mL of plasma on dry ice to Seattle Children's Main Lab. It is preferable that the sample is received by Seattle Children's Main Lab within 5 days from the date of collection.


Specimen Type Temperature Time
  Room temp N
  Refrigerated N
  Frozen 7 d



STAT Performed TAT
    8 d


Performing Laboratory

Baylor Miraca Genetics Laboratories

Biochemical Genetics Laboratory

2450 Holcombe, Grand Blvd. - Receiving Dock

Houston, TX 77021-2024


Phone Number: (713) 798-6555


Department: Send Outs

Phone Number: (206) 987-2563


Method: LC-MS/MS

Analytical Volume:


CPT Codes



Send Out Instructions

Reference Test Name Phenylbutyrate Metabolite Analysis
Reference Test Code 4650
Instructions Send frozen overnight to Baylor via FedEx. Will accept Saturday deliveries.