Test Catalog

Test ID: FENR    
Fentanyl Screen with Reflex, Random, Urine

Useful For Suggests clinical disorders or settings where the test may be helpful

Screening for drug abuse or use involving fentanyl, and confirmation of fentanyl if present in the screen

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

Testing begins with a screening assay. If the fentanyl screen is positive, then the liquid chromatography-tandem mass spectrometry confirmation with quantification will be performed at an additional charge.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

This procedure uses immunoassay reagents that are designed to produce a negative result when no drugs are present in a natural (ie, unadulterated) specimen of urine; the assay is designed to have a high true-negative rate. Like all immunoassays, it can have a false-positive rate due to cross-reactivity with natural chemicals and drugs other than those they were designed to detect. The immunoassay also has a false-negative rate to the antibody's ability to cross-react with different drugs in the class being screened for.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.


Screening cutoff concentration: 2 ng/mL

Interpretation Provides information to assist in interpretation of the test results

If the screen result is negative, fentanyl concentrations above 0.20 ng/mL were not detected.


If the screen result is positive, then confirmation by liquid chromatography tandem mass spectrometry will be performed.


The presence of fentanyl above 0.20 ng/mL or norfentanyl above 1.0 ng/mL is a strong indicator that the patient has used fentanyl.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Care should be taken when interpreting results since there are many factors (eg, fluid intake and other biologic factors) that may influence a urine test result. It is possible that substances other than those investigated in the specificity study may interfere with the test and cause either false-positive or false-negative results.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Gutstein HB, Akil H: Opioid analgesics. In: Brunton LL, Lazo JS, Parker KL, eds: Goodman and Gilman's: The Pharmacological Basis of Therapeutics. 11th ed. McGraw-Hill Companies; 2006:chap 21

2. Kerrigan S, Goldberger BA: Opioids. In: Levine ZB, eds. Principles of Forensic Toxicology. 2nd ed. AACC Press; 2003:187-205

3. DURAGESIC (fentanyl transdermal system). Package insert. Janssen Pharmaceutical Products. LP; 2006

4. Baselt RC: Disposition of Toxic Drugs and Chemicals in Man. 8th ed. Biomedical Publications; 2008:616-619

5. Langman LJ, Bechtel LK, Meier BM, Holstege C: Clinical toxicology. In: Rifai N, Horvath AR, Wittwer CT, eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier; 2018:832-887