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Interpretive Handbook

Test 62723 :
Drug Screen, Prescription/OTC, Chain of Custody, Serum

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

This test looks for a broad spectrum of prescription and over-the-counter (OTC) drugs. It is designed to detect drugs that have toxic effects, as well as known antidotes or active therapies that a clinician can initiate to treat the toxic effect. The test is intended to help physicians manage an apparent overdose or intoxicated patient, to determine if a specific set of symptoms might be due to the presence of drugs, or to evaluate a patient who might be abusing these drugs intermittently. The test is not designed to screen for intermittent use of illicit drugs.


Drugs of toxic significance that are not detected by this test are: digoxin, lithium, and many drugs of abuse/illicit drugs, some benzodiazepines, and most opiates.


See Prescription and Over-the-Counter (OTC) Drug Screens Table 1 in Special Instructions.


Chain of custody is a record of the disposition of a specimen to document who collected it, who handled it, and who performed the analysis. When a specimen is submitted in this manner, analysis will be performed in such a way that it will withstand regular court scrutiny.

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

Detection and identification of prescription or over the counter drugs frequently found in drug overdose or used with a suicidal intent


This test is designed to qualitatively identify drugs present in the specimen; quantification of identified drugs, when available, may be performed upon client request.


Chain of custody is required whenever the results of testing could be used in a court of law. Its purpose is to protect the rights of the individual contributing the specimen by demonstrating that it was under the control of personnel involved with testing the specimen at all times; this control implies that the opportunity for specimen tampering would be limited.

Interpretation Provides information to assist in interpretation of the test results

The drugs we know can be detected by this test are listed in Prescription and Over-the-Counter (OTC) Drug Screens Table 1 in Special Instructions.


The pharmacology of each drug determines how the test should be interpreted. A detailed discussion of each drug is beyond the scope of this text. If you wish to have a report interpreted, call Mayo Medical Laboratories and ask for a toxicology consultant.


Mayo Medical Laboratories will only report reference ranges that we have determined to be clinically correlated. Other reference ranges are available from the literature, but since we have not validated them, we choose not to report them. We will gladly discuss them during a consultation and provide reference citations if requested.


Each report will indicate the drugs detected.

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

Not intended for therapeutic compliance testing.


Not intended for use in employment-related testing.


Not intended for drugs of abuse/illicit drug testing.


Not all drugs can be quantitatively extracted from the specimen, so accurate quantification may not be possible, and many do not have reference ranges.

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.

Drugs detected are presumptive. Additional testing may be required to confirm the presence of any drugs detected.

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

Porter WH: Clinical toxicology. In Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Fourth edition. Edited by CA Burtis, ER Ashwood. DE Bruns St. Louis, MO, Elsevier Saunders, 2006, pp 1287-1369