Drug screens are common tests used to detect the presence of certain substances in a person’s system. When reviewing the results of such a screen, an abbreviation frequently encountered is “AMP.” This designation indicates the test was designed to identify amphetamines, a class of compounds known for their stimulant effects. Understanding “AMP” on a drug screen involves exploring these substances and their interaction with the body.
Understanding Amphetamines
Amphetamines are central nervous system (CNS) stimulants. They increase neurotransmitter levels like dopamine and norepinephrine in the brain, leading to increased alertness, attention, and energy. This action can result in improved focus, wakefulness, and heightened physical activity.
Amphetamines are prescribed for medical conditions such as attention-deficit/hyperactivity disorder (ADHD), narcolepsy, and sometimes obesity or binge-eating disorder. Prescription amphetamines include Adderall, Vyvanse, and Dexedrine. When used as directed, these medications can effectively manage symptoms.
Beyond medical applications, amphetamines are also used illicitly. Unauthorized forms, known by street names like “speed,” “uppers,” or “ice” (crystal methamphetamine), are sought for their euphoric and energizing effects. Non-medical use is illegal and carries significant health risks.
How Amphetamines Are Detected
Drug screens detect amphetamines in biological samples, each with a specific detection window. Urine testing is the most common method, favored for its affordability and ease. Amphetamines are detectable in urine for 1-3 days after single use, or up to a week for chronic users. Initial urine screens use rapid, cost-effective immunoassay tests.
Immunoassays provide quick presumptive results but can yield false positives from structurally similar substances. Positive immunoassay screens are therefore followed by confirmatory tests like gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS). These advanced techniques precisely identify and quantify specific drug compounds, offering accurate and legally defensible results.
Blood tests offer a shorter detection window than urine, typically 12-24 hours after use, sometimes up to 60 hours. They are used for immediate impairment assessment in emergency rooms or legal contexts. Saliva tests are a non-invasive option, detecting amphetamines for up to 48 hours, useful for on-site screenings.
Hair follicle tests offer a longer historical overview of substance use. They can reveal amphetamine use for up to 90 days by analyzing hair segments. Traces incorporate into the hair shaft, providing a record of past use. While excellent for chronic use, they may not show very recent use, as it takes 7-10 days for substances to reach the hair shaft.
Factors Influencing Detection and Results
Amphetamine detection windows vary based on individual and substance factors. Amount and frequency of use are primary determinants; higher doses or chronic use lead to longer detection as the substance accumulates. Metabolic rate plays a role, with faster metabolisms eliminating substances more quickly. Metabolism is influenced by age, health, organ function (liver and kidneys), and genetics.
Body composition also affects detectability. Substances can be stored in fatty tissues, so higher body fat might retain metabolites longer. Hydration levels impact urine tests; excessive fluid intake can dilute a sample, potentially requiring retesting. Urine pH also influences excretion rates, with more acidic urine leading to faster elimination.
Drug tests can produce “false positive” results, indicating amphetamines when none were consumed. This occurs due to cross-reactivity with certain prescription and over-the-counter medications sharing similar chemical structures. Examples include decongestants (pseudoephedrine), antidepressants (bupropion, trazodone), and weight-loss medications (phentermine).
Conversely, “false negative” results occur when amphetamines are present but not detected. This happens if drug concentration is below the test’s cutoff, or if the sample is excessively diluted. Adulterants can also interfere, leading to inaccurate negative results.
Medical Uses and Test Interpretation
A positive amphetamine drug screen does not automatically confirm illicit use. Many prescribed medications contain amphetamine compounds or metabolize into them. These are prescribed for conditions like ADHD, narcolepsy, weight management, or binge-eating disorder. Thus, a positive screen could be due to a legitimate prescription for drugs like Adderall, Vyvanse, or Dexedrine.
When a preliminary screen is positive, a confirmatory test is performed. These tests differentiate between amphetamine compounds and their metabolites, providing precise identification. This is important for distinguishing prescribed medications from illicit substances.
Individuals undergoing drug testing should inform the testing administrator or Medical Review Officer (MRO) about any prescription medications. Providing documentation of valid prescriptions allows the MRO to properly interpret results, ensuring legitimate use is not mistaken for illicit use. This disclosure is crucial for accurate and fair interpretation.