Tryptophan
Use
Determination of plasma tryptophan concentration may aid in evaluating nutritional status and metabolic disorders related to amino acid imbalances. It is clinically useful in assessing disorders in the tryptophan metabolic pathway and related neurological or metabolic conditions.
Special Instructions
Not provided.
Limitations
This assay has been analytically validated under CLIA regulations but has not been cleared or approved by the U.S. Food and Drug Administration; limitations include lack of FDA clearance and potential preanalytical sample integrity concerns such as hemolysis affecting results. Non‑fasting samples acceptable only in pediatric patients.
Methodology
Mass Spectrometry
Biomarkers
Result Turnaround Time
10 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
2 mL
Minimum Volume
0.25 mL
Container
sodium heparin (green‑top) tube
Collection Instructions
Collect plasma after overnight fast (or at least 4 hours after a meal) if possible; non‑fasting acceptable for pediatric patients; separate plasma from cells as soon as possible and freeze below ‑20 °C.
Patient Preparation
Overnight fast or ≥4 hours post‑prandial (non‑fasting acceptable for pediatric).
Storage Instructions
Freeze below ‑20 °C.
Causes for Rejection
Gross hemolysis
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | Unacceptable |
| Refrigerated | 7 days |
| Frozen | 28 days |