Drug Monitoring, Phosphatidylethanol (PEth), Blood
Also known as: Alcohol use biomarkers, Alcohol Metabolite, PEth
Use
Phosphatidylethanol (PEth) is an abnormal phospholipid formed in the presence of ethanol, incorporated in red blood cell membranes. As a direct and long‑window biomarker of alcohol consumption, PEth provides more specific detection than EtG/EtS and can indicate ethanol ingestion over multiple days (1–2 weeks, potentially up to 4 weeks in chronic users). Measuring key homologues—PEth 16:0/18:1 (POPEth) and PEth 16:0/18:2 (PLPEth)—supports identification of abstinence or probable chronic drinking in new patients, transplant candidates, and those undergoing CNS depressant therapy. Effective April 17, 2023. (Quest131 Directory and FAQ FAQs.293).
Special Instructions
Not provided.
Limitations
The test may not detect a single drink or casual drinking; a negative result does not definitively indicate abstinence, and a positive result suggests chronic or frequent drinking. Reference ranges for PLPEth are not well‑established and may change with new data. These limitations should be considered when interpreting results. (Quest FAQs.293)
Methodology
Mass Spectrometry
Biomarkers
LOINC Codes
- 97606-8
- 97607-6
- 97607-6
- 97606-8
Result Turnaround Time
3-5 days
Related Documents
For more information, please review the documents below
Specimen
Whole Blood
Volume
2 mL (0.5 mL minimum)
Minimum Volume
0.5 mL
Container
EDTA (lavender‑top) tube
Collection Instructions
Standard blood draw; collect in office or Quest Patient Service Center
Causes for Rejection
Non–whole blood samples; non‑EDTA tube
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 5 days |
| Refrigerated | 30 days |
| Frozen | 30 days |