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Diazepam Levels Blood Test

Last updated May 13, 2019

Approved by: Maulik P. Purohit MD, MPH

The Diazepam Levels Blood Test helps determine the level of diazepam in blood.

What are other Names for this Test? (Equivalent Terms)

  • Valium Levels Blood Test

What is the Diazepam Levels Blood Test? (Background Information)

  • Diazepam, also known as valium, is one of the most commonly prescribed anti-anxiety medications. The medication is also used to treat alcohol withdrawal and induce anesthesia for minor surgeries, among other uses
  • Diazepam levels peak in blood, 1-2 hours after its oral administration. They remain for up to 10-40 hours prior to being broken down in the liver into a variety of products, including N-desmethyldiazepam
  • Administration via injection causes its levels to peak within 15 to 30 minutes, while an intravenous administration causes the levels to peak within 5 minutes
  • Like other drugs, diazepam must be kept within a certain range to prevent unwanted side effects. If levels are too high, it may result in toxicity; if levels are too low, diazepam may not be of therapeutic value
  • The Diazepam Levels Blood Test helps determine the level of diazepam in blood. It is used when adjusting the initial dose, and to ensure that diazepam levels stay within an acceptable range

What are the Clinical Indications for performing the Diazepam Levels Blood Test?

Following are the clinical indications for performing the Diazepam Levels Blood Test:

  • Monitoring diazepam therapy
  • Confusion
  • Altered mental status
  • Tremors
  • Headache
  • Slurred speech
  • Increased heart rate

How is the Specimen Collected for the Diazepam Levels Blood Test?

Following is the specimen collection process for Diazepam Levels Blood Test:

Sample required: Blood

Process of obtaining blood sample in adults:

  • A band is wrapped around the arm, 3-4 inches above the collection site (superficial vein that lies within the elbow pit)
  • The site is cleaned with 70% alcohol in an outward spiral, away from the zone of needle insertion
  • The needle cap is removed and is held in line with the vein, pulling the skin tight
  • With a small and quick thrust, the vein is penetrated using the needle
  • The required amount of blood sample is collected by pulling the plunger of the syringe out slowly
  • The wrap band is removed, gauze is placed on the collection site, and the needle is removed
  • The blood is immediately transferred into the blood container, which has the appropriate preservative/clot activator/anti-coagulant
  • The syringe and the needle are disposed into the appropriate “sharp container” for safe and hygienic disposal

Preparation required: No special preparation is needed prior to the test.

What is the Significance of the Diazepam Levels Blood Test Result?

  • Diazepam levels should be between 0.5 and 2.0 mg/L. A high value (greater than 3 mg/L) for the Diazepam Levels Blood Test may indicate diazepam toxicity

The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.

Additional and Relevant Useful Information:

  • Certain factors, such as alcohol consumption, may interfere with the results of the Diazepam Levels Blood Test
  • Diazepam has the ability to cross the placenta. Pregnant women MUST consult their physician prior to beginning diazepam therapy, as diazepam may cause birth defects

Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider of the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.

The following DoveMed website link is a useful resource for additional information: 


Please visit our Laboratory Procedures Center for more physician-approved health information:


References and Information Sources used for the Article:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Jan. 12, 2016
Last updated: May 13, 2019