TRYPTOPHAN

Specimen Required
Collect specimen after overnight fast or 4 hours after a meal. Non-fasting samples are acceptable for pediatric patients. Draw blood in a green sodium heparin tube. Centrifuge, remove plasma from cells and send 2.0 mL plasma (0.3 mL minimum) frozen in a screw-capped plastic vial.

Alternate Specimen
Plasma: EDTA or lithium heparin

Rejection Criteria
Gross hemolysis, Room temperature samples

Methodology
Liquid Chromatography - Tandem Mass Spectometry

Stability
Room temperature: Unacceptable; Refrigerated: 7 days; Frozen: 28 days

Reference Range
By report

Performed
Tuesday, Thursday, Friday

Turnaround Time7-11 days
Test CodeTRYPT
CPT-4 Code (s)
82131
LOINC Codes
20659-9

Warde
Medical
Laboratory