Understanding Your Laboratory Test: What It Is, How It Is Done, and What Your Results Mean
A test that measures the level of benzodiazepine medications in your blood to help monitor treatment or check for drug use.
{"Measures benzodiazepine drugs like Valium, Xanax, or Ativan in blood","Used to ensure proper dosing or detect misuse","Results help doctors adjust treatment safely","May be ordered for medication monitoring or toxicology screening"}
Key facts at a glance
- LOINC
- 111299-4
- Short code
- BENZOS
- Synonyms
- Benzodiaz Msmt SerPl
- Category
- chemistry
- Sample
- serum
- Container
- Red-top serum clot tube or plasma separator tube (PST, green-top/heparin); alternatively EDTA plasma (lavender-top) for some assays
- Units
- N/A
- Ref low
- 100
- Ref high
- 200
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Immunoassay (e.g., enzyme immunoassay, fluorescence polarization immunoassay); positive results typically confirmed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) or gas chromatography-mass spectrometry (GC-MS)
- CPT
- 80307
- SNOMED
- 395081007
- Specimen volume
- 1-2 mL serum or plasma (minimum 0.5 mL)
- Stability
- Room temperature: 24 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 30 days for most benzodiazepines; avoid repeated freeze-thaw cycles
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 50
- TAT
- 4–48 hours
- Order
- routine
This test is a laboratory analysis that helps your healthcare provider evaluate how your body is functioning. By examining a small sample, it can detect a medical condition early, confirm a suspected diagnosis, or monitor how well a current treatment is working for you.
The Benzodiazepine test measures the amount of benzodiazepine medications in your blood serum. Benzodiazepines (often called 'benzos') are prescription drugs commonly used to treat anxiety, insomnia, seizures, and muscle spasms. Common examples include diazepam (Valium), lorazepam (Ativan), alprazolam (Xanax), and clonazepam (Klonopin).
The test is usually done by collecting a small sample, most often a blood draw from a vein in your arm or a urine sample, depending on what your provider has ordered. The procedure takes only a few minutes, causes minimal discomfort, and the sample is then sent to a laboratory for analysis.
A healthcare professional will draw a blood sample from a vein in your arm. The sample is then sent to a laboratory for analysis. You do not need to fast before this test. However, it is important to tell your doctor about all medications, supplements, or herbal products you are taking, as some substances may affect the test results.
Your results are compared with standard reference ranges to show whether your values fall within normal limits. Normal results usually suggest no cause for concern, while abnormal values do not always indicate a serious problem. Your healthcare provider will explain what your specific numbers mean and whether any follow-up testing or treatment is needed.
Test results show whether benzodiazepines are present in your blood and at what level. Therapeutic levels indicate the drug is within the range expected for medical treatment. Subtherapeutic levels may suggest the dose is too low or the medication is not being taken as prescribed. Supratherapeutic or unexpected levels may indicate overuse, misuse, or potential toxicity.
Reference range
Negative (cutoff typically 100-200 ng/mL for serum/plasma depending on assay); therapeutic and toxic ranges vary by specific benzodiazepine (e.g., diazepam, lorazepam, alprazolam, midazolam, nordiazepam, oxazepam, temazepam, clonazepam, etc.)N/A
No fasting required. Specimen should be collected prior to next scheduled dose for therapeutic drug monitoring (trough level). Patient should be advised to disclose all prescription, over-the-counter, and herbal medications as benzodiazepines are commonly part of polysubstance panels.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
This test is primarily used for therapeutic drug monitoring (TDM). It helps ensure patients are receiving the correct dose of their prescribed benzodiazepine for effective treatment while minimizing side effects. The test is also used in emergency settings to evaluate suspected drug overdose, in substance abuse evaluation, or during forensic investigations. Additionally, it may be used to assess medication compliance and detect unauthorized use of these controlled substances.
Frequently asked questions
Why do I need this test?
How long do benzodiazepines stay in blood?
Will this test show all types of benzodiazepines?
Does a positive result mean I'm misusing my medication?
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