Understanding Your Medical Test: What It Is, How It Is Performed, and What Your Results Mean
A test to measure the amount of barbital, a barbiturate medication, in your blood.
{"Barbital is an older type of sedative/hypnotic medication rarely used today","This test measures drug concentration to ensure proper dosing or detect overdose","The test uses a blood sample collected from a vein in your arm","Results help doctors monitor drug therapy or investigate unexplained sedation"}
Key facts at a glance
- LOINC
- 79225-9
- Short code
- BARB
- Synonyms
- Barbital Fld-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top vacutainer tube (no anticoagulant) for serum; alternatively, gray-top sodium fluoride/potassium oxalate tube
- Units
- N/A
- Ref low
- 0
- Ref high
- 0
- Critical range
- — – 30 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Gas Chromatography-Mass Spectrometry (GC-MS) or Immunoassay
- CPT
- 80345
- SNOMED
- 395259009
- Specimen volume
- 5 mL of whole blood; minimum 1 mL of serum required
- Stability
- Serum stable for 7 days at 2-8°C; 4 weeks at -20°C; avoid repeated freeze-thaw cycles
- Hemolysis max
- 100
- Lipemia max
- 100
- Icterus max
- 50
- TAT
- 24–72 hours
- Order
- routine
What is this test and why might my healthcare provider recommend it for me?
The Barbital blood test measures the amount of barbital in your blood serum. Barbital is a barbiturate—a class of medications that act as central nervous system depressants. Historically, barbital was used as a sedative and hypnotic (sleep aid), but it has largely been replaced by safer alternatives in modern medicine. This test is not commonly ordered today but may be used in specific clinical situations such as monitoring patients on barbital therapy, evaluating suspected overdose, or in forensic or drug testing contexts.
How is the test performed, and what should I expect before, during, and after the procedure?
A healthcare professional will collect a blood sample from a vein in your arm using a small needle. The sample will be sent to a laboratory for analysis. The test measures the concentration of barbital in micrograms per milliliter (μg/mL) or milligrams per liter (mg/L) in your serum. No special preparation is typically required, but follow your doctor's instructions regarding timing of the blood draw in relation to your last dose of any medication.
What do my test results mean, and how will my doctor use them to guide my care and treatment plan?
Results are interpreted based on the therapeutic range and clinical situation. Therapeutic drug monitoring helps ensure drug levels are within the effective range while avoiding toxicity. Your doctor will explain your specific results considering your medical history, symptoms, and treatment goals. Abnormally high levels may indicate overdose or accumulation, while very low levels may suggest the medication is not reaching therapeutic effectiveness.
Reference range
Reference ranges are not well established for therapeutic use; barbiturates are generally not detectable in unexposed individuals. Detection indicates exposure to barbiturate-class drugs. Quantitative results should be interpreted in correlation with clinical presentation and history.N/A
No special patient preparation required. Inform the laboratory of any prescription medications, particularly anticonvulsants, sedatives, or sleep aids containing barbiturates (e.g., phenobarbital).
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
The primary clinical significance of the barbital test includes: (1) Therapeutic drug monitoring for patients currently on barbital therapy, (2) Evaluation of suspected drug overdose or poisoning, (3) Assessment of unexplained central nervous system depression or coma, and (4) Forensic or toxicology investigations. Since barbital is rarely prescribed today, this test is uncommon in routine clinical practice. When used, it helps clinicians make informed decisions about medication dosing, determine the cause of clinical symptoms, and guide appropriate treatment interventions.
Frequently asked questions
Why would I need this test?
Is the test safe?
How long does it take to get results?
What happens if my levels are too high?
Sources
- 1
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- 3
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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