Serum/plasma fentanyl and norfentanyl concentration (qualitative/quantitative immunoassay)
This test measures the presence and levels of fentanyl and its active metabolite, norfentanyl, in your blood. It helps detect recent opioid exposure, including illicit use or prescribed medications containing these compounds.
["Detects recent opioid exposure, including prescription or illicit use, by checking for fentanyl and its metabolite."]
Key facts at a glance
- LOINC
- 105202-6
- Short code
- fentaNYL+Norfentanyl pnl Bld LC/MS/MS
- Synonyms
- fentaNYL+Norfentanyl pnl Bld LC/MS/MS
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 0
- Ref high
- 100
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- lc-ms-ms
- CPT
- 83721
- SNOMED
- 113079007
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why This Test Is Done
Your healthcare provider may order this test if you’ve experienced symptoms like confusion, drowsiness, slowed breathing, or overdose. It’s also used in cases of suspected opioid poisoning, drug screening for legal or workplace reasons, or monitoring patients on opioid therapy for compliance or toxicity.
What to Expect Before the Test
No special preparation is needed. You’ll provide a blood sample (usually from a vein in your arm) by a phlebotomist. If you’re on blood thinners, let your provider know before the test.
What the Results Mean
Positive results indicate recent fentanyl or norfentanyl exposure. High levels may suggest recent use, while low or absent levels mean no detectable exposure. Results are qualitative (present/absent) or quantitative (measured concentration), depending on the assay.
Common Causes of Positive Results
Positive results can occur from prescribed fentanyl or norfentanyl medications, illicit fentanyl use, or contamination (e.g., in counterfeit drugs). False positives are rare but may occur with certain medications or substances.
Reference range
Optimal: <100 mg/dLN/A
Fasting for 12-14 hours preferred. Water is permitted. Avoid alcohol for 24 hours before the test.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
Opioid drug screening (fentanyl metabolites)
Frequently asked questions
How often do I need this test?
What if my results are positive?
Can I drink alcohol before this test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy