What lab orders are needed to check for substance use and alcohol level?

Laboratory Orders for Drug Screening and Alcohol Level Testing

For comprehensive substance use screening, order a urine drug screen (UDS) and blood alcohol level test. 1, 2

Urine Drug Screen (UDS)

Standard Panel

A standard 10-panel urine drug screen typically tests for:

• Amphetamines
• Barbiturates
• Benzodiazepines
• Cocaine
• Marijuana (THC)
• Methadone
• Opiates
• Phencyclidine (PCP)
• Methamphetamine
• Propoxyphene 1

Collection Method

• Collect a clean-catch urine specimen in a sterile container
• Supervised collection may be necessary to prevent tampering
• Document any medications the patient is currently taking to help interpret results 2, 1

Important Considerations

• Standard immunoassay screens have limitations:
  • Cannot distinguish between prescribed medications and illicit substances
  • May produce false positives with certain medications
  • May miss synthetic opioids like fentanyl or oxycodone 1, 3
• Consider ordering confirmatory testing via gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-mass spectrometry (LC-MS) for positive results 1, 4
• Detection windows vary by substance:
  • Opioids: 1-3 days
  • Cannabis: 1-3 days for occasional use, up to 30+ days for heavy use
  • Amphetamines: up to 48 hours
  • Cocaine: 2-3 days 1

Blood Alcohol Level

Test Options

• Blood alcohol concentration (BAC) test
  • Most accurate method
  • Provides quantitative results
  • Correlates well with level of impairment 2
• Alternative: Breath alcohol testing
  • Non-invasive option
  • Good proxy for blood alcohol concentrations
  • Primarily used by law enforcement and alcohol treatment programs 2

Timing Considerations

• Blood alcohol levels decline at approximately 0.015-0.020% per hour
• Testing should be performed as soon as possible for accurate results 2
• An elevated alcohol level may interfere with psychiatric evaluation 2

Additional Testing Considerations

Clinical Context

• For adolescents, the American Academy of Pediatrics recommends screening all youth ages 12-21 for substance use 2
• In emergency department settings, drug and alcohol screening is particularly important for patients presenting with psychiatric symptoms 2
• For patients in juvenile justice settings, both self-report and bioassay testing may be necessary 2

Pitfalls to Avoid

• False positives can occur with certain medications:
  • Pseudoephedrine can cause false-positive for amphetamines
  • Some antidepressants can cause false-positive for benzodiazepines
  • Antibiotics can cause false-positive for opiates 1, 3
• Standard opiate screens may miss synthetic opioids like oxycodone or fentanyl 4
• False negatives occur in up to 56% of cases when comparing standard UDS to comprehensive LC-MS testing 5

Documentation

• Document the reason for testing
• Note all current medications that might affect results
• Consider establishing a relationship with laboratory toxicologists to assist with result interpretation 1

By ordering both a urine drug screen and blood alcohol level test, you'll obtain comprehensive information about potential substance use that can guide further assessment and treatment decisions.