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Interpretive Handbook

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Test 80372:
Barbiturate Confirmation, Urine

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

Barbiturates represent a class of drugs that were originally introduced as sleep inducers. Butalbital is also used to control severe headaches. Mephobarbital and phenobarbital are frequently used to control major motor (grand mal) seizures. These drugs are commonly abused as "downers" to induce sleep after an amphetamine- or cocaine-induced "high."

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

Detecting drug abuse involving barbiturates such as amobarbital, butalbital, pentobarbital, phenobarbital, and secobarbital

Interpretation Provides information to assist in interpretation of the test results

The presence of a barbiturate in urine at >200 ng/mL indicates use of 1 of these drugs.

 

Most of the barbiturates are fast acting; their presence indicates use within the past 3 days.

 

Phenobarbital, commonly used to control epilepsy, has a very long half-life. The presence of phenobarbital in urine indicates that the patient has used the drug sometime within the past 30 days.

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

No significant cautionary statements. This test is very specific for these compounds.

 

For chain-of-custody information, see COCH/9426 Chain-of-Custody Processing.

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.

Negative

Positives are reported with a quantitative GC-MS result.

Cutoff concentrations:

IMMUNOASSAY SCREEN

<200 ng/mL

 

BUTALBITAL BY GC-MS

<100 ng/mL

 

AMOBARBITAL BY GC-MS

<100 ng/mL

 

PENTOBARBITAL BY GC-MS

<100 ng/mL

 

SECOBARBITAL BY GC-MS

<100 ng/mL

 

PHENOBARBITAL BY GC-MS

<100 ng/mL

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

Baselt RC, Cravey RH: Disposition of Toxic Drugs and Chemicals in Man. 3rd edition. Chicago, IL, Year Book Medical Publishers, 1989