Understanding Your Laboratory Test: What It Measures, How It Works, Sample Collection, and How to Read Your Results

Published: August 9, 2026Updated: August 17, 2026

A hair test that detects barbiturate use over the past several months.

Quick summary

{"Tests for barbiturate drugs in a hair sample","Can detect drug use over 1-3 months or longer","Used for medication monitoring or substance abuse assessment","A small hair sample is collected from the scalp","Results are reported as positive or negative"}

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC: 91047-1
Short code: BARBHAIR
Synonyms: Barbiturates Hair Ql Scn
Category: chemistry
Sample: serum
Container: Foil-wrapped hair specimen envelope or sterile screw-top container for hair collection
Units: N/A
Ref low: 3.5
Ref high: 7.2
Fasting: false
Population: adult
Sex: all
Age range: 18–65 years
Method: screen
CPT: 80307
SNOMED: 395080008
Specimen volume: 100-200 mg of hair (approximately 50-100 strands, 3-6 cm in length, proximal to scalp)
Stability: Room temperature: stable for up to 2 weeks; Refrigerated (2-8°C): stable for 1 month; Frozen (-20°C or below): stable for long-term storage up to 1 year. Store in dark, dry conditions.
Hemolysis max: 500
Lipemia max: 1000
Icterus max: 500
TAT: 48–72 hours
Order: routine

The Hair Barbiturate Screen test looks for barbiturates in your hair. Barbiturates are prescription medications that affect the central nervous system. They are used for conditions like seizures, anxiety, and sleep disorders. This test can show whether you have taken these medications over the past few months.

How does this test work once my sample reaches the laboratory?

When you take a medication, tiny amounts enter your bloodstream. As your hair grows, these substances become trapped in the hair shaft. By testing a small piece of hair, doctors can learn about your medication use over time—typically the past 1 to 3 months, depending on hair length.

How is the sample collected for this test, and how should I prepare?

A small bunch of hair (about 100-120 strands) is cut from the back of your head, close to the scalp. The collection is quick and generally painless. If head hair is not available, body hair may be used as an alternative.

What do the results of this test mean for my overall health?

Results are typically reported as 'Positive' (barbiturates detected) or 'Negative' (no barbiturates detected). A positive result means barbiturates were found in your hair sample within the detection window. Your doctor will explain what this means for your specific situation.

Reference range

NCBI: Uric Acid Male 3.5-7.2 mg/dL; Female 2.5-6.8 mg/dLN/A

Specimen: serum

No special patient preparation is required. Patients should be advised that hair treatments such as bleaching, dyeing, or perming may affect drug concentration results. Approximately 100-200 mg of hair (pencil-width bundle) is typically needed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

This test helps healthcare providers monitor medication compliance, evaluate drug exposure, and assess for possible substance misuse. It may be used in pain management, addiction treatment programs, forensic investigations, or when monitoring patients on long-term barbiturate therapy.

Hair testing is especially useful because it provides a longer detection window compared to blood or urine tests, offering a broader picture of drug use patterns over time.

Frequently asked questions

Will hair color or treatment affect the test?

Hair treatments like bleaching, dyeing, or perming may potentially affect test results. However, modern testing methods are generally robust. Always inform the testing facility about any recent hair treatments.

Can secondhand exposure cause a positive result?

It is unlikely that secondhand exposure would cause a positive result in hair testing, as the test detects drugs that have been incorporated into the hair over time through regular use.

How long can barbiturates be detected in hair?

Barbiturates can typically be detected in hair for up to 3 months or longer, depending on hair length and the specific drug. Each centimeter of hair represents approximately one month of growth.

Is this test painful?

No, hair collection is quick and painless. Only a small amount of hair is cut from near the scalp.

Sources

1
Mayo Clinic Laboratories - Barbiturates, HairSource
2
American Academy of Clinical Toxicology - Hair Testing GuidelinesSource
3
MedlinePlus - Drug TestingSource

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.

Medical Disclaimer

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