Interpretive Handbook

Test 8610 :
Chlordiazepoxide, Serum

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Chlordiazepoxide (Librium) is a benzodiazepine widely used in the treatment of anxiety. It is also used in the treatment of alcohol withdrawal symptoms, as a premedication for anesthesia, in obstetrics during labor, as a muscle relaxant, and as an anticonvulsant. Toxic manifestations can include confusion, ataxia, sedation, tachycardia, hyperreflexia, and hypertension. Fatalities resulting from overdose are rare.

Useful For Suggests clinical disorders or settings where the test may be helpful

Monitoring chlordiazepoxide therapy  


Because chlordiazepoxide has a wide therapeutic index and dose-dependent toxicity, routine drug monitoring is not indicated in all patients

Interpretation Provides information to assist in interpretation of the test results

A therapeutic dose will yield a serum concentration of 1 to 3 mcg/mL.


In the treatment of delirium tremens, concentrations up to 10 mcg/mL are typical.


Toxic concentration: > or =15 mcg/mL

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

The specimen must be protected from light. 

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Therapeutic concentration: 1.0-3.0 mcg/mL

Chronic use: 5.0-10.0 mcg/mL

Toxic concentration: > or =15.0 mcg/mL


The reference range cited (5.0-10.0 mcg/mL) relates to chronic therapy with chlordiazepoxide. Concentrations in the range of 1.0-3.0 mcg/mL are typical for occasional, non-chronic use. Concentrations as high as 80 mcg/mL may be observed in aggressive therapy with chlordiazepoxide for treatment of delirium tremens.

Clinical References Provides recommendations for further in-depth reading of a clinical nature

1. Judd LL: The therapeutic use of psychotropic medications: antianxiety or anxiolytic medications. In Harrison's Principles of Internal Medicine. 12th edition. Edited by JD Wilson, E Braunwald, KJ Isselbacher, et al. New York, McGraw-Hill Book Company, 1991, pp 2143-2144

2. Scharf MB, Khosla N, Brocker N, Goff P: Differential amnestic properties of short- and long-acting benzodiazepines. J Clin Psychiatry 1984;45:51-53