Advanced Urine Drug Testing
NOAH Clinical Laboratory utilizes the latest technology available to detect a wide array of drugs and metabolites in urine samples. We employ modern LC-MS/MS instrumentation to provide results in the quickest, most accurate fashion possible. Use of confirmatory quantitation methods provide many benefits when compared to point-of-care (POC) testing and screening assays.
Benefits of Quantitative Confirmation Analysis
Applications of toxicology testing include:
- Determining whether patients have recently taken their prescribed medication
- Discovering if non-prescribed medications or illicit drugs have been used
- Monitoring compliance of medications with a high abuse potential
- Prevention of misuse, addiction, or diversion
Benefits of Quantitative Confirmation Analysis with LC-MS/MS
Drug Screen Limitations
- Lack specificity
- Drug classes vs. individual drugs
- Ex: Opiates vs 6-monoacetylmorphine
(heroin metabolite)
- Cross reactivity
- High concentrations of other drugs can yield false positives
- Ex: DRI Methadone EIA false positive with Tapentadol and metabolites
- Lack sensitivity
- Cutoffs typically lower
- Ex: Opiate cutoff = 300 ng/mL vs 50 ng/mL
- Not comprehensive
- Covers approx. 20 drug classes and without focus on metabolites
- Ex: Detection of noroxycodone (oxycodone metabolite) would indicate biological metabolism, not spiking of oxycodone into the sample
- Semi-quantitative at best
Interpretation of a Positive Drug Screen
- Patient is compliant and took the prescription as directed
- Patient added drug to the urine after collection
- Patient took one dose prior to collection
- Patient took another drug which cross- reacts with the test, i.e. a false-positive
- Ex: Pseudoephedrine can give a “Positive” result for an amphetamine screening test
Interpretation of a Negative Drug Screen
- Patient is not compliant
- Patient did not follow dosing regimen
- Less frequent or lower dose
- Drug present but below the cutoff
- Dilute or adulterated urine
- False-negative
- Test does not react with drug of interest
- Appropriately targeted test may not be available
- Altered pharmacokinetic variables
- Ultra-fast metabolizer – no parent drug present, only metabolite
- Poor drug absorption
Strengths of LC-MS/MS Analysis
- High specificity
- Can differentiate between individual drugs
- No cross reactivity
- Utilizes 3 unique analyte properties to ID
- Increased sensitivity
- Cutoffs are lower than immunoassay techniques
- Reduced false negatives
- Comprehensive
- Can detect many individual compounds with respective metabolites
- Current capability is 75 analytes
- Quantitative
- Use of certified reference materials allow accurate quantitative values