Clinical Toxicology Testing Flashcards
Impacts of substance abuse
Lost productivity
Increased health costs
Increased cost to the courts
Specimens for Clinical Toxicology Testing
Urine
Blood/Plasma
Gastric fluids
Meconium
Oral fluids
Sweat
Hair
Placenta and cord blood/tissues
Why urine is a preferred specimen
Easy collection
More concentrated than in blood
Screening assay compatibility
Metabolite detection
Limitations of urine as a clinical toxicology specimen
Can’t correlate ingestion time/amount/frequency nor degree of impairment
Misses certain drugs - Ritalin and oral hypoglycemics
Drug detection time lines in urine
<24hrs - Alcohol, Heroin,
3 days - Opiates
4 days - MDMA, Amphetamines, Cocaine
Days to Weeks - the B’s Barbiturates and Benzodiazepines
3 weeks - Methadone
30 days - Marijuana
Testing methods and associated issues
Immunoassays
LC/MS/MS - Opioid ID
GC/MS - Full scan
Advantages and Limitations of Immunoassay testing
Advantages: improved TAT, detects broad class of drugs
Limitations: prone to cross-reactivity and false pos/negs
- pos immunaassay is anything form A to Z
What is KIMS and when do we use it?
Kinetic Interaction of Micro-particles in Solution
Used to detect benzodiazepines but interfered by oxaprozin (FP)
Describe the principle of KIMS
Ab bound to microparticles
Drugs conj to aminodextran
No drugs: amino-dextran agglut with micro particles = increased absorbance
Drugs: drugs bind Ab on micro particles os amino-dextran cant agglutinate = low absorbance
ie more drug =less absorbance
Advantages of GC/MS and LC/MS confirmatory testing
Very specific
Limitations of GC/MS and LC/MS confirmatory testing
- More expensive/resource driven
- Limited by quality of extraction and chromatographic properties
Specimen integrity issues
- Internal dilution - drinking lots of water
- External dilution - adding water to sample
- Tampering - adding adulterants or masking agents
- Substitution - submits sample thats not their own
How do we test for specimen integrity?
Temperature (baseline)
pH (adulterants)
Creatine and SG (dilution and substitution)
Non-clinical testing scenarios
Clinical tox is not used for
-employment
-insurance
-anything relating to the law
-determination of compliance or impairment
STAT drug testing
Not recommended
- non-specific
- doesn’t meaningfully influence acute medical management
