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Center for Substance Abuse Treatment. Improving Treatment for Drug-Exposed Infants. Rockville (MD): Substance Abuse and Mental Health Services Administration (US); 1993. (Treatment Improvement Protocol (TIP) Series, No. 5.)

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Improving Treatment for Drug-Exposed Infants.

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Appendix C - Urine toxicology Guidelines

  1. Specific urine toxicology techniques. Drug toxicology tests are most commonly performed on urine, since most drugs and their breakdown products are excreted in the urine in higher concentrations than in the blood, and because urine toxicology tests are often inexpensive and quick. Alcohol toxicology tests are routinely performed on blood and breath as well as urine.
    1. Screening tests. Overall, drug screening tests are rapid, technically simple, and economical. Generally, these tests are sensitive, meaning they can detect evidence of small amounts of drugs or drug metabolites. However, they are less specific and less reliable than confirmatory tests. In other words, drug screening tests are known to produce false-positive and false-negative test results.
      Screening tests are typically batched, meaning that multiple urine samples are screened together. When a batch of multiple urine samples is found to be positive, the individual urine samples may be retested to identify the positive specimen. Once the urine sample has been identified as testing positive by a screening test, the specimen is retested with a more specific (and more expensive) confirmatory test. Two of the more common screening tests are thin-layer chromatography (TLC) and immunoassays.
      • TLC is a practical, economical, and sensitive method of detecting drugs in urine specimens. TLC is particularly useful because multiple specimens can be tested, and more than one drug can be determined for each application.
        The test involves applying urine specimens onto a glass plate, which is sprayed with various reagents. The appearance and position of spots on the plate are used to identify the drug or drugs being sought. The certainty of the identification depends on the efficiency of the procedure, the ability of the technicians performing the assays, and the ability of those making the identification.
        There are TLC screening tests for most drugs of abuse, including the opioids, the amphetamines, the barbiturates, cocaine, marijuana, glutethimide, and the phenothiazines.
      • Immunoassay techniques, such as the enzyme multiplied immunoassay technique (EMIT), are commonly used drug screening techniques in part because they are sensitive, quick, and require a small sample. Also, these tests can be easily automated and performed by a minimally trained individual not trained in toxicology. These tests utilize complex immunochemistry and the production of drug antibodies in an interaction with enzymic detectors to reflect the presence of various drugs subject to misuse.
        In addition to EMIT, other examples of immunoassay techniques include radioimmunoassays and fluorescence polarization immunoassays. Most drugs of abuse are detectable by immunoassays, including the opioids, the amphetamines, the barbiturates, the cannabinoids, cocaine, and PCP.
    2. Confirmatory tests. The basic principle of confirming a positive drug test is to retest the same urine sample with a different type of test. It is standard to first test body fluids with sensitive but less specific tests, and to confirm positive test results by retesting with sensitive and highly specific tests. Confirmatory tests generally have few false positive results.
      Gas chromatography / mass spectrometry (GC / MS) is the procedure generally accepted by the scientific community for the confirmed identification of drugs of abuse. GC / MS also allows for quantitative analysis. Most drugs of abuse can be confirmed with GC / MS.
  2. Forensic drug testing. Since the word forensic indicates a relation to law or legal issues, forensic drug testing describes drug testing processes that meet legal standards, and which may be scrutinized in court. Forensic drug testing involves accepted standards for urine collection and storage, chain of custody, and laboratory standards.
    On April 11, 1988, the "Mandatory Guidelines for Federal Workplace Drug Testing Programs" were published in the Federal Register. This Federal effort described scientific and technical requirements for forensic urine drug tests and procedures. It also described procedures for identifying, evaluating, and certifying laboratories to perform forensic urine drug testing for Federal Agency Drug-Free Workplace Programs.
    While these standards were developed for workplace drug testing, they are equally applicable to forensic urine drug testing regarding drug-exposed infants.
    1. Laboratories that have received certification have been assessed and verified with respect to quality control. Laboratories are assessed with respect to adequacy of laboratory facilities, the expertise and experience of laboratory personnel, the excellence of the laboratory's quality control program, performance of the laboratory on proficiency tests, and compliance with standards as reflected in the laboratory inspection. A list of certified laboratories is published monthly in the Federal Register.
    2. The guidelines specify that the initial or screening test shall be an immunoassay that meets the requirement of the Food and Drug Administration for commercial distribution. Also, the guidelines specify that all specimens identified as positive on the screening test shall be confirmed using GC / MS.
      It should be mentioned that not all laboratories are certified. Further, not all laboratories use GC / MS for confirmation of positive screenings. Thus, addiction treatment professionals should directly inquire about certification, and whether the laboratory does a GC / MS confirmation. In particular, addiction treatment professionals should ask the laboratory what specific tests are being used for screening and confirmation.
  3. Factors contributing to false-positive, false-negative, and inconclusive results. The appropriate collection, handling, and testing of urine specimens is critical to avoid false-positive, false-negative, and inconclusive test results.
    1. Specimen collection. The acceptable standard for collecting urine specimens is observed urine collection, to avoid deceptive switching or purposeful contamination. Contamination of specimen container, preparing the surfaces through which test materials are to be collected, and cleaning the skin with isopropyl alcohol may cause false-positive results.
    2. Specimen handling. Several errors may cause inconclusive or misinterpreted test results. Such errors include mislabeling, specimen confusion, misidentification of the subject, and breaks in the chain of custody. Contamination of equipment, failure to clean glassware, and operator error may result in test result error.
    3. Other factors. Errors may occur during any type of scientific measurement process, including drug testing. Human mistakes such as test equipment operator error may cause test error. Since many drug tests rely upon technician interpretation, human error can occur during this last stage.
      Diluted urine can result in false-negative or inconclusive test results. Also, various drug tests will identify the presence of over-the-counter (OTC) drugs, prescribed medications, and some foods that are chemically related to drugs of abuse. Historic examples include the amphetamine-related OTC drugs phenylpropanolamine and ephedrine registering an amphetamine test as positive, as well as foods that contain poppy seeds registering an opioid test as positive. Many drug tests are routinely modified to reduce cross-reactivity and to increase drug specificity.
  4. Drug detection times in urine. The duration of detection times for all drugs depend to a great extent on the volume, dose, and duration of drug use. For example, marijuana is commonly detected three days following inhalation of a single joint, but can be detected as much as thirty days following cessation of chronic, high-dose use. Elimination times may differ between neonates and adults, but there is a paucity of information on elimination times in neonates. While the elimination rates of drugs are variable, the following table displays an approximate guideline of duration for detecting various drugs of abuse in urine.
    The elimination of some drugs can be influenced by changes in urine pH, which can be altered by the ingestion of some acidic or basic substances. For example, PCP excretion can be somewhat accelerated by the ingestion of cranberry juice.
  5. Alternate methods of screening for substance abuse. Other methods of screening for prenatal substance abuse are not readily available, and may not be acceptable in a court of law. These include testing of newborn meconium and radioimmunoassay of maternal hair. A recent large-scale prospective study of newborns shows that improved detection of exposed newborns can be achieved with meconium analysis.

Drug Durations

Drug Durations
Drug Duration
Amphetamines48 hours
Alcohol12 hours
Barbiturates10-30 days
Valium4-5 days
Cocaine24-72 hours
Heroin24 hours
Marijuana3-30 days
Methaqualone4-24 days
Phencyclidine3-10 days
Methadone3 days


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