Your Blood Test: What It Is, How It Is Done, and How to Understand Your Results
A blood test that measures the level of barbiturates in your serum or plasma to monitor drug therapy or detect potential overdose.
{"Barbiturate test measures sedative drug levels in blood","Used to monitor treatment and check for overdose or misuse","Sample is collected from a vein in your arm","Results help doctors adjust medication doses safely","Commonly tested for phenobarbital, pentobarbital, and similar drugs"}
Key facts at a glance
- LOINC
- 110114-6
- Short code
- BARB
- Synonyms
- Barbiturates Msmt SerPl
- Category
- chemistry
- Sample
- serum
- Container
- Red-top serum tube (no anticoagulant) or serum separator tube (SST)
- Units
- N/A
- Ref low
- 15
- Ref high
- 40
- Critical range
- — – 50000 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Immunoassay (e.g., enzyme immunoassay, chemiluminescent immunoassay, or cloned enzyme donor immunoassay); confirmation by Gas Chromatography-Mass Spectrometry (GC-MS) or Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
- CPT
- 80345
- SNOMED
- 395155005
- Specimen volume
- 1-2 mL of serum
- Stability
- Room temperature: 24 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 30 days. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 25
- TAT
- 4–24 hours
- Order
- routine
What Is This Test? This laboratory test measures specific substances in a sample of your blood to help your healthcare provider evaluate your overall health, screen for certain medical conditions, or monitor a treatment plan you may already be following.
The barbiturate test measures the amount of barbiturate drugs in your blood. Barbiturates are sedative-hypnotic medications that affect the central nervous system. They are prescribed for conditions such as epilepsy, insomnia, and as anesthesia during surgery. This test helps your doctor ensure you have the right amount of medication in your system—not too little to be ineffective, and not too much to cause harmful side effects.
How Is the Test Performed? A trained healthcare professional will draw a small sample of blood, usually from a vein in your arm, using a thin needle. The collection takes only a few minutes, and the sample is then sent to a laboratory for analysis. You can typically return to your normal activities right away.
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 tube and sent to a laboratory for analysis. You do not need to fast or make any special preparations before this test, unless your doctor instructs otherwise. The procedure typically takes only a few minutes.
Why Might I Need This Test? Your provider may order this test as part of a routine checkup, to help find the cause of symptoms you are experiencing, to screen for health risks before they become serious, or to track how well a current treatment is working over time.
Your doctor may order this test for several reasons: to monitor the effectiveness of barbiturate therapy if you are taking medication for seizures or sleep disorders; to check for drug overdose or poisoning; to ensure drug levels are within the therapeutic range and not toxic; or to evaluate unexplained symptoms such as extreme drowsiness, confusion, or breathing problems.
Understanding Your Results: Your results will be compared with established reference ranges, and a value outside those ranges does not always mean something is wrong. Your healthcare provider will review the findings with you, explain what they mean in the context of your overall health, and discuss any follow-up steps, such as additional testing or changes to your care plan.
Results are usually reported as either present (detected) or absent (not detected), or as a specific concentration. Therapeutic levels vary depending on the specific barbiturate and your medical condition. Your doctor will interpret your results based on your individual health situation, medication dosage, and symptoms. Do not change your medication dose without consulting your healthcare provider.
Reference range
Negative: <200 ng/mL (cutoff varies by laboratory). Therapeutic ranges vary by specific barbiturate (e.g., phenobarbital 15-40 mcg/mL).N/A
No special preparation required. Note the time of last dose and specific barbiturate ingested if known. Avoid sample collection from the arm receiving IV fluids or medications.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
The barbiturate test is clinically significant for monitoring patients on long-term barbiturate therapy, particularly for epilepsy management. It helps prevent toxicity by ensuring drug levels remain within the therapeutic range. The test is also crucial in emergency settings for diagnosing barbiturate overdose, which can cause severe respiratory depression, coma, or death. Additionally, it may be used in forensic or substance abuse screening contexts.
Frequently asked questions
Are there any risks with this test?
How long does it take to get results?
What should I tell my doctor before the test?
What does it mean if my results are high?
Can the test detect all types of barbiturates?
Sources
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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