Specimen Collection

Casual urine

Reference Intervals

REPORT: The screen is reported as either Detected or Not Detected (qualitative result only).

Uncertainty of Measurement : 10% at the level of 200 ng/mL.

Turnaround Time: Within 1 day

Availability : Drug screens can be performed after hours and on weekends for urgent samples (AED/CED), or if approved by the on-call Chemical Pathologist. The request form must be clearly marked ' Urgent' and the laboratory must be alerted by telephone (via Lablink) before the sample is sent.

Diagnostic Use and Interpretation

Drugs detected:

Benzodiazepines are extensively metabolised, and generally the parent compounds are not detected in urine.

Because diazepam is a long acting benzodiazepine, its metabolites can be detectable in urine from 1 day to 6 weeks after ingestion, depending on dose and duration of intake.

Diazepam metabolites are nordiazepam, temazepam, and oxazepam therefore their presence together in a urine drug screen result is consistent with diazepam use.

This screening test (immunoassay) detects the following types of benzodiazepine drugs:

• Alprazolam
• Bromazepam
• Chlordiazepoxide
• Clobazam
• Clonazepam
• Diazepam
• Estazolam
• Flunitrazepam
• Flurazepam
• Lorazepam
• Lormetazepam
• Medazepam
• Nitrazepam
• Oxazepam
• Prazepam
• Temazepam
• Triazolam

The benzodiazepine immunoassay screen provides only a preliminary analytical test result for benzodiazepines as a class, and does not differentiate between these individual drugs.

Like all immunoassay based tests, there is the possibility of false positives and false negatives, depending on factors such as urine dilution and the particular drug(s) ingested. For specific patient queries, please contact the laboratory.

IMPORTANT: Low immunoassay cross reactivity to nitrazepam and clonazepam may cause a false negative screen if low levels are present. To confirm the presence of nitrazepam or clonazepam, please request GCMS or specify these drugs in the clinical details (see below).

Plasma clonazepam levels can also be requested for monitoring compliance. This is analysed by a different highly specific method (LCMS), so false positives and negatives should not occur.

Confirmation and identification of specific benzodiazepines:

Mass spectrometry (MS) analysis is available which can confirm and identify the specific drug. However, it will only be performed if requested to further identify the specific benzodiazepine.

The MS assay at LabPlus can identify:

• Nordiazepam, oxazepam, and temazepam (metabolites of diazepam)
• Lorazepam
• Alpha hydroxyalprazolam (metabolite of alprazolam)
• Alpha hydroxytriazolam (metabolite of triazolam)
• Alpha hydroxymidazolam (metabolite of midazolam)
• 7-aminoclonazepam (metabolite of clonazepam)
• 7-aminoflunitrazepam (metabolite of flunitrazepam)
• 7-aminonitrazepam (metabolite of nitrazepam)

Click on the link below for more information on Drug Screens:

Drug screen -Clinical management

Drug screen- Evidential purposes

Contact Information

Emails to chemicalpathologist@adhb.govt.nz will receive priority attention from the on-call chemical pathologist.

If the query concerns a specific patient please include the NHI number in your email.

If email is not a suitable option, please contact the on-call chemical pathologist via Lablink (Auckland City Hospital ext. 22000 or 09-3078995).

Individual chemical pathologists may be contacted but will not be available at all times.

After-hours : contact Lablink (Auckland City Hospital ext. 22000 or 09-3078995) or hospital operator for on duty staff after hours.

Dr Samarina Musaad (Clinical Lead) : SamarinaM@adhb.govt.nz ext. 22402

Dr Cam Kyle: CampbellK@adhb.govt.nz ext 22052

Dr Weldon Chiu: WeldonC@adhb.govt.nz ext. 23427

Dr Campbell Heron: CHeron@adhb.govt.nz ext. 23427

Last updated at 09:25:30 22/01/2024