Complete Blood Count (CBC) Test: What It Is, Why It Is Done, and What Your Results Mean
A screening test to detect the presence of barbiturate medications in your blood.
{"This test checks for barbiturate drugs in your blood sample","It is commonly used to monitor medication levels or check for drug use","Results help doctors ensure proper dosing or diagnose overdose"}
Key facts at a glance
- LOINC
- 30249-7
- Short code
- BARBS
- Synonyms
- Barbiturates SerPl Scn-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top serum tube or plasma separator tube (PST)
- Units
- N/A
- Ref low
- 200
- Ref high
- 300
- Critical range
- — – 10000 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- screen
- CPT
- 80307
- SNOMED
- 395112001
- Specimen volume
- 1-2 mL serum or plasma
- Stability
- Room temperature: 24 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 30 days
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 50
- TAT
- 1–24 hours
- Order
- routine
The complete blood count, commonly called a CBC, is a routine blood test that measures the different cells circulating in your blood, including red blood cells, white blood cells, and platelets, giving your healthcare provider a broad picture of your overall health and helping detect many common conditions early.
The barbiturate blood test is a screening test that detects the presence of barbiturate drugs in your serum (liquid part of blood). Barbiturates are medications that slow down brain activity and are used as sedatives, sleeping pills, or to treat seizures. Examples include phenobarbital, pentobarbital, and secobarbital.
This test is performed to screen for a wide range of health problems such as anemia, infections, and blood disorders, to investigate symptoms like fatigue, weakness, fever, or unexplained bruising, and to monitor an existing medical condition or how well treatments, including chemotherapy, are affecting your blood cells.
This test may be ordered for several reasons: to monitor therapeutic drug levels in patients taking barbiturates for seizure disorders, to check for accidental or intentional overdose, or to detect illegal use of barbiturate drugs. Your doctor will determine if this test is appropriate based on your medical condition and symptoms.
The test is done with a simple blood draw: a healthcare professional cleans a spot on your arm, usually the inside of the elbow, wraps a band around your upper arm, inserts a small needle to collect a sample into a tube, and then removes the needle and applies a bandage. The sample is sent to a laboratory, and the procedure usually takes only a few minutes.
A healthcare professional will draw a small blood sample from a vein in your arm using a needle. The blood is collected in a special tube and sent to a laboratory for analysis. The test is a screening method, so if positive, confirmatory testing may be needed to identify the specific barbiturate present.
Your results show whether your blood cell counts fall within normal ranges. A low red blood cell count may suggest anemia, a high white blood cell count can point to infection or inflammation, and abnormal platelet levels may affect clotting. Abnormal values do not always mean serious illness, so your provider will interpret them along with your symptoms, history, and other tests.
Results are typically reported as positive or negative. A negative result means no barbiturates were detected in your blood. A positive result indicates the presence of barbiturates. Your doctor will interpret the results based on your medical history, symptoms, and the specific barbiturate being tested. Therapeutic drug monitoring ensures medication levels are within the effective and safe range.
Reference range
Negative (cutoff concentration typically 200-300 ng/mL for most barbiturates)N/A
No fasting required. Inform clinician of all medications including prescription barbiturates, over-the-counter drugs, and supplements prior to testing.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
This test is clinically significant for monitoring patients on long-term barbiturate therapy, particularly for epilepsy management. Maintaining therapeutic levels prevents both breakthrough seizures (too low) and toxicity (too high). It is also crucial in emergency settings for diagnosing barbiturate overdose, which can cause severe drowsiness, confusion, respiratory depression, and potentially coma or death.
In forensic and addiction medicine settings, this test helps detect barbiturate misuse or abuse. The test may also be used in pre-employment screening or substance abuse treatment programs. Understanding barbiturate levels helps healthcare providers make informed decisions about treatment adjustments, detox protocols, or overdose management.
Frequently asked questions
Do I need to fast before this test?
How long does it take to get results?
Are there any risks from the blood draw?
What should I tell my doctor before the test?
Sources
- 1
- 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 15, 2026. · Read our editorial policy