Benzodiazserplmcnc
A benzodiazepine blood test measures the amount of benzodiazepine medications in your blood to help monitor treatment effectiveness and safety.
{"Measures benzodiazepine drug levels in your blood serum or plasma","Helps doctors monitor if your medication dose is in the therapeutic range","Used to diagnose suspected overdose or poisoning","Timing of the blood draw relative to your last dose is important","Different benzodiazepines stay in the body for different lengths of time"}
Key facts at a glance
- LOINC
- 11024-7
- Short code
- BENZOS
- Synonyms
- Benzodiaz SerPl-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top serum tube (no anticoagulant) or plasma separator tube (PST/heparin). Avoid gel barrier tubes if mass spectrometry confirmation is anticipated.
- Units
- N/A
- Ref low
- 0
- Ref high
- 50
- Critical range
- — – 5000 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- Immunoassay (EIA/EMIT) with confirmatory Gas Chromatography-Mass Spectrometry (GC-MS) or Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
- CPT
- 80307
- SNOMED
- 395171001
- Specimen volume
- 5-10 mL of whole blood yielding 2-5 mL of serum or plasma
- Stability
- Room temperature: 24 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 30 days. For extended storage, freeze at -80°C.
- Hemolysis max
- 100
- Lipemia max
- 100
- Icterus max
- 50
- TAT
- 4–72 hours
- Order
- routine
What is this test?
A benzodiazepine blood test is a laboratory test that measures the concentration of benzodiazepine medications in your blood serum or plasma. Benzodiazepines are a class of prescription medications commonly used to treat conditions such as anxiety, insomnia, seizures, muscle spasms, and as sedation before medical procedures. Common benzodiazepines include diazepam (Valium), lorazepam (Ativan), alprazolam (Xanax), clonazepam, and midazolam.
Why is this test done?
Your doctor may order this test for several reasons: (1) Therapeutic drug monitoring - to ensure your current dose is within the effective and safe range; (2) Suspected overdose - if you or your doctor suspects you have taken too much medication; (3) Compliance checking - to verify that you are taking your medication as prescribed; (4) Evaluating drug interactions - to see if other medications are affecting benzodiazepine levels in your blood.
How is the test performed?
A healthcare professional will draw a blood sample from a vein in your arm using a small needle. The blood will be collected in a special tube and sent to a laboratory for analysis. The test requires a serum or plasma sample, which is obtained by processing your blood in a centrifuge to separate the liquid portion from the blood cells. The actual testing is typically done using immunoassay or chromatography techniques.
What do the results mean?
Test results are interpreted based on the specific benzodiazepine being measured and its therapeutic range. Results below the therapeutic range may indicate that the dose is too low to be effective. Results within the therapeutic range generally indicate an appropriate dose. Results above the therapeutic range may suggest overdose or accumulation of the drug, which can be dangerous. Your doctor will interpret your results considering your specific medication, dosage, and individual health factors.
Reference range
Negative: <50 ng/mL (varies by laboratory and specific benzodiazepine compound; screening cutoff commonly 50-200 ng/mL). Therapeutic ranges vary by drug: Diazepam 100-1000 ng/mL, Nordiazepam 100-700 ng/mL, Lorazepam 10-80 ng/mL, Oxazepam 200-1400 ng/mL, Temazepam 200-1100 ng/mL, Alprazolam 5-40 ng/mL.N/A
No fasting required. Patients should be informed about specimen collection. For forensic or compliance testing, chain of custody procedures must be followed. Disclose all prescription medications, over-the-counter drugs, and supplements to avoid misinterpretation.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Frequently asked questions
Do I need to fast before this test?
Does the timing of my dose affect the test?
How long do benzodiazepines stay in my blood?
Can this test detect all types of benzodiazepines?
Is the test safe?
Sources
- 1
- 2
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 15, 2026. · Read our editorial policy