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Test Code LAB355 Amino Acids, Quantitative, Urine

Performing Laboratory

St. Louis Children's Hospital - Metabolic Genetics

Reference Values

Reference Range:

Age-dependent

See "Amino Acid Reference Values"

Critical Values: None established

Last Reviewed

08/2025

Methodology

Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

Specimen Requirements

Patient Preparation: See Urine Collection instructions

Container/Tube  
Preferred: Random: A clean, plastic urine container(s) with no preservative.
Acceptable: Clean, screw-cap container with no preservative.
Collection Volume: 5.0 mL (minimum of 1.0 mL) of a random collection

Submission Container/Tube: If sending specimen from an outside facility, place urine in a 10 mL screw-cap plastic transport vial and freeze STAT. Place specimen to dry ice to keep frozen during transport.
Special Instructions: Send to lab promptly.

Barnes-Jewish Hospital Note:

Call Laboratory Medicine resident at digital pager 314-747-1320 for approval before obtaining specimen.

 

Submit an entire 24-hour urine collection in a plain, brown urine container.
Additional Information:
1. Starting and ending times of collection are required.
2. Follow instructions for Urine Collection in Special Instructions.
3. Urine timed measurement is performed at an additional charge per 24-hour collection (CPT Code-81050).

Additional Information

FOR SLCH CORE LABORATORY USE ONLY

Lab Processing Instructions:

  1. Mix specimen well and make two aliquot tubes.
  2. Aliquot one sample into a 10-mL plastic screw cap urine tube for Met. Gen. testing and freeze in MET. GEN. basket in freezer #1. 
  3. Aliquot a second sample for LUO urine creatinine testing. Give aliquot to the PRO bench and let them know they have a Met. Gen. specimen that needs to be frozen ASAP post analysis in freezer #1.
  4. Place the original collection container (with or without any remaining sample) in freezer #1.

NOTE: If specimen needs to be shared with UA bench, make sure they are aware that the specimen is shared, and original container needs to be placed in Met. Gen. basket in freezer #1.

 

Processed Volume: 5.0 mL (minimum 1.0 mL) urine

NO SPECIMEN SHOULD BE REJECTED FOR VOLUME. PLEASE CALL THE FLOOR TO NOTIFY THE NURSE THAT ADDITIONAL SPECIMEN IS NEEDED, SHOULD BE COLLECTED, AND SENT TO LAB TO ADD TO WHAT IS ALREADY COLLECTED. GIVE ALL SPECIMENS TO METABOLIC GENETICS TO DECIDE IF QNS.


Analyte Stability: 

Specimen Type Temperature    Time              
urine (no preservative)     Ambient  1 hour
  Refrigerated      NA  
  Frozen   indefinetly    

Test Classification and CPT Code

82139

Test Classification: This test was developed and its performance characteristics determined by St. Louis Children's Hospital Clinical Laboratory. It has not been cleared or approved by the U.S. Food and Drug Administration.

Logistics

Day(s) Test Set Up: Monday-Friday
Cut-off time: Varies, batched once per day in a.m.
Turnaround Time: 3-5 days

Limitations

  • NA

LOINC

35087-6

Sample Rejection

Mislabeled or unlabeled specimen

Specimens collected with preservative

Barnes-Jewish Hospital Additional Information:

 

For BJH Laboratory Use Only
Laboratory Processing Instructions:BJH Core Lab will forward to the performing laboratory.