Complete Blood Count (CBC): What This Test Is and Why Your Doctor Orders It
This test measures the level of benzodiazepine medications in your blood to monitor treatment or check for drug use.
{"Benzodiazepines are prescription medications used for anxiety, sleep disorders, and seizures","This test helps doctors ensure proper medication levels or detect misuse","Blood is drawn from a vein in your arm for this test","Results help guide treatment decisions and ensure medication safety","Follow your doctor's instructions regarding medication before testing"}
Key facts at a glance
- LOINC
- 46977-5
- Short code
- BENZOCFM
- Synonyms
- Benzodiaz SerPl Cfm-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top vacuum blood collection tube (no anticoagulant) for serum; alternatively, plasma separator tube (PST) with lithium heparin or sodium fluoride/potassium oxalate (gray-top) for plasma
- Units
- N/A
- Ref low
- 50
- Ref high
- 100
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- confirm
- CPT
- 80347
- SNOMED
- 30463007
- Specimen volume
- 3-5 mL of whole blood yielding approximately 1.5-2.5 mL of serum or plasma
- Stability
- Room temperature: 24 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 30 days. Avoid repeated freeze-thaw cycles. Specimens should be transported on ice or refrigerated when delays in processing are anticipated.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 24–96 hours
- Order
- routine
The complete blood count, or CBC, is a common blood test that measures the different cells circulating in your blood, including red blood cells, white blood cells, and platelets. Each of these cell types plays an important role in your health, from carrying oxygen throughout your body to fighting infections and helping your blood clot properly after an injury.
The benzodiazepine blood test is a laboratory test that measures the amount of benzodiazepine drugs in your blood serum or plasma. Benzodiazepines are a class of prescription medications commonly used to treat conditions such as anxiety, insomnia, muscle spasms, and seizures. This confirmatory test is highly accurate and can detect specific types of benzodiazepines and their levels in your bloodstream.
Your doctor may order a CBC as part of a routine health checkup to get an overall picture of your health, or to help investigate symptoms such as fatigue, weakness, fever, unexplained bruising, or frequent infections. It is also used to monitor known conditions like anemia or infections, and to check how certain medications or treatments are affecting your blood cells over time.
Doctors may order this test for several reasons: (1) To monitor therapeutic drug levels in patients taking benzodiazepines long-term, ensuring the medication is at effective but safe levels; (2) To evaluate patients who may be experiencing symptoms of overdose or poisoning; (3) To check for benzodiazepine use in cases of suspected drug misuse or abuse; (4) To help diagnose the cause of unexplained symptoms like excessive drowsiness, confusion, or breathing problems.
The test is done through a simple blood draw, usually from a vein in the inside of your elbow or the back of your hand. A healthcare professional will clean the area, wrap an elastic band around your upper arm to make the vein easier to see, insert a small needle, and collect the sample into a tube. The entire process typically takes just a few minutes.
A healthcare professional will draw a small blood sample from a vein in your arm using a needle. The blood will be collected in a special tube and sent to a laboratory for analysis. The test uses confirmatory methods to accurately identify and measure benzodiazepine levels. You may need to avoid taking your medication before the test if instructed by your doctor, as this could affect the results.
Your results will show whether the levels of your red blood cells, white blood cells, and platelets fall within the normal reference ranges. Values that are higher or lower than expected can point to conditions such as anemia, infection, inflammation, or clotting disorders. Your doctor will interpret the numbers together with your symptoms, medical history, and physical exam before reaching any conclusion.
Test results are reported as either positive (indicating benzodiazepines are present) or negative, and may include specific levels if the medication is being monitored for therapeutic purposes. Your doctor will interpret the results based on your medical history, the specific medication you take, and your treatment goals. Therapeutic ranges vary depending on the specific benzodiazepine and the condition being treated.
A CBC is considered very safe and poses minimal risk. The most common side effects are minor, such as slight pain, tenderness, or bruising at the needle site, and some people may feel briefly lightheaded during or right after the draw. Serious complications are rare, and most people can return to their normal activities immediately after the test is complete.
The risks associated with this blood test are minimal and similar to any standard blood draw. You may experience slight pain or bruising at the needle site, and in rare cases, infection or excessive bleeding may occur. The test itself does not pose any significant health risks.
Reference range
Negative (below confirmatory cutoff, typically <50-100 ng/mL depending on specific benzodiazepine analyte and laboratory cutoff). Therapeutic and toxic ranges vary by specific benzodiazepine compound.N/A
No special patient preparation is typically required. Patients should inform their healthcare provider of all medications, including prescription benzodiazepines, over-the-counter drugs, and herbal supplements prior to specimen collection.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
This test has important clinical applications in medication management and patient safety. For patients on long-term benzodiazepine therapy, regular monitoring helps maintain effective treatment doses while minimizing risks of toxicity or dependence. The test is also valuable in emergency settings for diagnosing overdose, particularly in cases of unexplained sedation or respiratory depression. In addiction medicine, this test helps healthcare providers identify benzodiazepine misuse, which is important for appropriate intervention and treatment planning.
Results from this confirmatory test can guide dosing adjustments, help identify drug interactions, and ensure patient compliance with prescribed regimens. For patients with liver or kidney disease, monitoring benzodiazepine levels is particularly important as these conditions can affect drug metabolism and clearance from the body.
Frequently asked questions
Do I need to fast before this test?
How long does it take to get results?
Can this test detect all types of benzodiazepines?
Will my insurance cover this test?
What should I tell my doctor before the test?
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 16, 2026. · Read our editorial policy