MarkerTest Distribution
Why Urine Drug Testing (UDT)?
BETTER DETECTION =BETTER PATIENT CARE AND OUTCOMES
Urine Drug Testing (UDT) is part of the ongoing monitoring process of patients on chronic opioid therapy. It is used to confirm the presence of prescribed medications and to detect the presence of unauthorized substances. UDT is considered a valuable tool to track progress toward treatment goals and to guard against no-nmedical use and diversion. The confirmatory urinary drug test is laboratory-based and employs the principles of high performance liquid chromatography – tadem mass spectrometry (LC-MS/MS). LC-MS/MS is considered to be the “gold standard” of urinary drug testing.
According to the National Institute on Drugs of Abuse, "Drug testing by urinalysis has been suggested and in many cases implemented for prospective and current employees in industry; for personnel of the armed forces; for parolees and bail seekers in civilian court systems; for workers in the transportation industry; and for individuals who serve as role models, such as nationally known athletes. Two factors have led to the widespread use of urine drug tests: technical developments in testing methods and the growing demand for drug testing. Society is becoming increasingly aware of the impact of drug use on public safety and of the financial impact on industry of lost time and productivity. The annual loss of productivity of employees has been estimated at $100 billion for alcohol and drug abuse, a third of which is due to drug abuse alone."
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Why perform urine drug screens instead of blood screens or even hair analysis? Urine drug screens are the gold standard in drug testing. While a given drug may be detected in a blood sample only for a few hours, the same drug can be detected in a urine sample for as long as one to three days or even for as long as 30 days, depending on the chemical nature of the drug.
These drug panels are designed to classify substances as either "present" or "absent" according to predetermined cutoff thresholds. Definitive identification of a specific drug and/or its metabolite(s) requires more sophisticated tests, such as liquid chromatography/mass spectrometry (LC/MS) and liquid chromatography/mass spectrometry/mass spectrometry (LC/MS/MS). The urine drug screening method chosen depends upon the question that needs to be answered.
The immunoassay drug tests, which are designed to classify substances as either "present" or "absent" according to a predetermined cutoff threshold, are the most commonly used methods. Immunoassays are based on the principle of competitive binding, using antibodies to detect the presence of a particular drug or metabolite in a urine sample. A known amount of an antibody and the drug or metabolite that has been labeled with an enzyme are added to the urine sample. The drug or metabolite in the sample competes with the labeled drug or metabolite for binding sites on the antibody to form antigen-antibody complexes. The amount of enzyme-labeled antigen that binds with the antibody is inversely proportional to the amount of the drug and/or its metabolite(s) in the sample.
The biggest advantages of immunoassays are their ability to quickly and simultaneously detect drugs in urine as well as their minimal cost. The biggest disadvantage of immunoassays is that they vary in the type of compounds that can be detected. Some immunoassays detect specific drugs, while others identify only classes of drugs. An immunoassay's ability to detect drugs will vary according to the drug's concentration in the urine and the assay's cutoff concentration. Any response above the cutoff level is reported as positive, and any response below the cutoff is reported as negative. (So for example, if the cutoff is set at 50 ng/mL, a result of 49 ng/mL will be reported as negative.) Immunoassays are also subject to cross-reactivity. In other words, substances with similar, and sometimes dissimilar, chemical compositions might cause a test to appear positive for the target drug. Because of the potential for cross-reactivity, samples that test positive for classes of drugs by immunoassay might need to be retested in the laboratory using an alternative method if specific identification of the drug is required.
A number of single-use immunoassay devices are commercially available for point of care (POC) testing for classes of commonly misused drugs. POC devices typically use immunochromatographic methods that produce visually read results. Used alone, POC testing by immunoassay is often inadequate in patient-centered urine drug testing, since most physicians want to identify the presence of a specific drug or metabolite, and not merely the drug class.
Most POC tests are based on competitive binding to antibodies by drug(s) present in the urine and a drug conjugate that is bound to a porous membrane. In the absence of the drug in the sample, a limited number of dye-conjugated antibodies bind the immobilized drug conjugate, forming a colored line (negative result) in the test window. When the amount of drug in a urine sample is equal to or greater than the cutoff concentration of a particular device, the drug saturates the antibody and prevents the antibody from binding the immobilized drug conjugate, so no line forms in the window (positive result). But this is a counterintuitive response. So some POC devices now operate more logically and produce a color for a positive result. POC devices have several advantages. They have a rapid turnaround time, are portable, are less expensive, and are seemingly easy to use. One particularly useful role for POC testing is to provide on-the-spot identification of illicit drug use.
Potential disadvantages of POC devices include the subjective nature of the qualitative assays, lack of adequate quality assurance and quality control (for example, the integrity of the test reagents following transportation and storage), data management issues, a limited menu of detectable drugs offered, and lack of evidence that using POC devices improves patient outcomes when compared with laboratory testing. Training of users should include quality issues and recognition of any device limitations. In contrast to testing laboratories, POC devices purchased from a manufacturer might not include independent scientific support, although most manufacturers offer toll-free hotlines for consultation. For these reasons, physicians should evaluate POC devices carefully before using them routinely. Physicians should also use such devices with caution to prevent misinterpretation of the results because most tests do not provide numbers on sensitivity or specificity.
Generally, more definitive laboratory-based procedures–such as GC/MS, LC/MS, and LC-MS/MS–are necessary to identify specific drugs in the following three circumstances.
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To specifically confirm the presence of a given drug, for example, that morphine is the opiate causing a positive immunoassay response
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To identify drugs not included in an immunoassay test
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When results are contested comparing qualitative and quantitative screening
The specimen collector meets with the patient to gather his or her insurance information, document demographic information from the patient's chart, and complete a requisition form.
Next the patient provides the urine sample, which may or may not be witnessed by the specimen collector. At this time, the specimen may be subjected to qualitative (point of care) testing either through a specialized cup or testing sticks. The collector then packages the urine sample and sends it to our partner labs in Florida, for evaluation.
When the urine sample arrives at our partner lab, a qualitative analysis is done first. The result of this test is either positive or negative. This tells the doctor "yes" or "no"–the patient is taking the prescribed drug or he or she isn't taking the prescribed drug. The physician receives these results within approximately 24 hours, and these results guide the physician in his or her treatment of the patient.
Next, a second test is performed on the sample. This is a quantitative analysis, and it's often called a "confirmation." This test determines the amount of a particular drug in the patient's system. The physician receives these results in two to four days. With this additional information, the physician can further refine his or her treatment plan.
Our partner lab normally performs a 12 to 23 - panel drug screen (more panels are possible). This test screens for the presence of amphetamines, barbiturates, benzodiazepines, cocaine, cannabinoids, methadone, opiates, propoxyphene, buprenorphine, oxycodone, and tramadol.
As with any group of people, physicians differ in their feelings about urine drug screening. In general, most physicians want to screen patients because screening benefits their patients.
It also reduces their liability when prescribing narcotics to their patients. Urine drug screening also allows physicians to assess a patient's degree of compliance with taking prescribed medications. In other words, urine drug screens tell physicians if a patient is taking the medications as prescribed-and if a patient is taking any drugs or substances that are not prescribed, or possibly prescribed by another physician/provider. Urine drug screening is also an excellent screening tool for a collection of deadly diseases called chemical dependency.
Urine drug screening is an essential feature of any pain management regimen because it allows the physician to monitor a patient's adherence to treatment. Urine drug screening also identifies any illicit or unauthorized licit drugs, which might influence therapeutic decisions and could negatively impact the doctor-patient relationship.
The rate of substance abuse among individuals who are prescribed scheduled drugs continues to rise. One of our jobs at MarkerTest Distribution is to help Physicians minimize the misuse, abuse, and diversion of these drugs. Because self-reported drug use by chronic pain patients to their treating physicians is not always reliable, there is a very real need for consistent, reliable urine drug testing. Statistics suggest that up to 20 percent of patients who are prescribed opioid medications abuse or misuse those medications, whether they are being treated by a primary care physician or a pain management specialist. Also, 21 percent of individuals who were prescribed opioid medications on a long-term basis had urine drug screens that were positive for illicit drugs or an unauthorized controlled substance even when they exhibited no aberrant behavior. Without consistent and reliable urine drug testing, this type of abuse remains unnoticed and untreated.
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If physicians want to use urine drug testing to improve the quality of care they offer their patients, but if they're not sure how to integrate it into their practices, MarkerTest Distribution Sales Manager can help.
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