Understanding Your Laboratory Test: What It Measures and Why It Matters
This test detects the presence of barbiturate medications in the vitreous fluid of the eye, commonly used in forensic investigations.
{"This test looks for barbiturate drugs (sedatives) in the eye's vitreous fluid","It is primarily used in forensic (post-mortem) investigations","Results help determine if barbiturate drugs were involved in a person's death","Vitreous fluid is often tested when blood samples are not available","This is not a routine clinical test for living patients"}
Key facts at a glance
- LOINC
- 27224-5
- Short code
- VBART
- Synonyms
- Barbiturates Vitf Ql
- Category
- chemistry
- Sample
- serum
- Container
- Sterile red-top Vacutainer tube (no anticoagulant) or sterile screw-top cryovial; specimen container must be labeled with chain of custody documentation
- Units
- N/A
- Ref low
- 3.5
- Ref high
- 7.2
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Immunoassay (EIA) with confirmatory Gas Chromatography-Mass Spectrometry (GC-MS) or Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
- CPT
- 80307
- SNOMED
- 439470001
- Specimen volume
- 1-2 mL of vitreous humor (minimum 0.5 mL required for analysis)
- Stability
- Vitreous fluid barbiturates are stable at room temperature (20-25°C) for 7 days, refrigerated (2-8°C) for 14 days, and frozen at -20°C for up to 6 months. For prolonged storage, maintain at -80°C.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 24–72 hours
- Order
- routine
What does this test check for, and what can the results tell my doctor about my health?
The Barbiturates test detects the presence of barbiturate medications in the vitreous fluid—the clear, gel-like substance that fills the space between the lens and retina in the eye. Barbiturates are a class of sedative-hypnotic drugs that were historically used for anxiety, sleep disorders, and seizure control. Examples include phenobarbital, pentobarbital, and amobarbital.
How is the sample for this test collected, and what can I expect during the collection process?
The sample (vitreous fluid) is collected from the eye using a needle and syringe in a procedure called vitreous aspiration. This is typically performed by a pathologist or trained medical professional, usually during a post-mortem examination (autopsy). Unlike blood tests, this procedure is not performed on living patients as part of routine care.
Why might my healthcare provider order this test, and how will the results be used in my care?
This test is primarily performed in forensic investigations to help determine the cause and manner of death. It may be ordered when: there is suspicion of drug overdose, death is unexplained, or when blood samples are unavailable or contaminated. Vitreous fluid is relatively isolated and can provide valuable toxicological information even when other samples are not suitable for testing.
Reference range
NCBI: Uric Acid Male 3.5-7.2 mg/dL; Female 2.5-6.8 mg/dLN/A
No patient preparation is required. Vitreous fluid is collected postmortem via needle aspiration from the vitreous chamber of the eye, typically through the lateral canthus. Procedure is performed by a pathologist or trained medical examiner. No fasting is necessary.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
In forensic pathology, detecting barbiturates in vitreous fluid can help determine whether these drugs played a role in a person's death. Barbiturate overdose can cause respiratory depression and death. A positive result may indicate accidental overdose, intentional self-harm, or in some cases, therapeutic use. The test helps forensic experts piece together what happened in cases involving unexplained deaths.
Frequently asked questions
Is this a test for living patients?
What do positive results mean?
Can this test distinguish between different barbiturates?
Why is vitreous fluid used instead of blood?
Sources
- 1LOINC Code ReferenceSource
- 2
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 17, 2026. · Read our editorial policy