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Test ID TRYPP Tryptophan, Plasma

Useful For

Investigating inadequate tryptophan intake and monitoring dietary treatment

Method Name

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

Reporting Name

Tryptophan, P

Specimen Type


Necessary Information

1. Patient's age is required.

2. Include family history, clinical condition (asymptomatic or acute episode), diet, and drug therapy information.

Specimen Required

Patient Preparation: Fasting (overnight preferred, 4 hours minimum). Infants should be drawn just before next feeding (2-3 hours without total parenteral nutrition: TPN if possible).

Collection Container/Tube:

Preferred: Green top (sodium heparin)

Acceptable: Lavender top (EDTA)

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL

Collection Instructions:

1. Centrifuge within 4 hours, if specimen is stored at refrigerated temperature, and aliquot plasma.

2. Send plasma frozen.

Specimen Minimum Volume

0.3 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Plasma Frozen 14 days

Reference Values

≤23 months: 17-75 nmol/mL

2 years-17 years: 23-80 nmol/mL

≥18 years: 29-77 nmol/mL

Day(s) Performed

Monday through Friday

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
TRYPP Tryptophan, P 20659-9


Result ID Test Result Name Result LOINC Value
82955 Tryptophan 20659-9
34619 Interpretation (TRYPP) 59462-2
38056 Reviewed By 18771-6

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

Report Available

3 to 5 days

NY State Approved



If not ordering electronically, complete, print, and send an Inborn Errors of Metabolism Test Request (T798) with the specimen.