Urine drug testing is a widely used method to detect the presence of illicit substances or prescription medications in an individual’s system. Employers, legal entities, and healthcare providers often rely on these tests for various purposes. A common question arises regarding the viability of using a urine sample that is not freshly collected, specifically one that has been stored for several days, such as three days. The effectiveness and implications of using such a sample for accurate drug detection are significant concerns.
What Happens to Stored Urine
When urine is stored outside the body, particularly at room temperature, it undergoes several physical and chemical transformations. Bacteria naturally present begin to multiply rapidly. This proliferation consumes urea, a major component of urine, converting it into ammonia, which significantly alters the sample’s chemical composition.
The increased ammonia production impacts the urine’s pH level, causing it to become more alkaline over time. This shift from the typical slightly acidic to moderately alkaline range can compromise the sample’s integrity. Drug metabolites, which are the specific substances laboratories test for, can also degrade. Some drug metabolites can diminish in concentration, making them harder to detect accurately.
Creatinine, a marker for urine concentration and validity, also naturally degrades when urine is stored. Its breakdown can lead to lower-than-expected levels, signaling an altered or non-fresh sample. Additionally, a stored urine sample will cool to ambient temperature, deviating from the normal human body temperature range of approximately 90-100°F (32-38°C), which is a parameter typically checked during collection.
How Stored Urine Affects Test Results
The physical and chemical changes that occur in stored urine compromise the reliability of drug test results. The degradation of drug metabolites means their diminished concentration can lead to a false negative result. This indicates the absence of drugs when they were, in fact, present.
Conversely, the proliferation of bacteria and the resulting shifts in pH can interfere with the chemical reagents used in drug assays. This interference can produce a false positive result for certain substances, incorrectly indicating drug use. An aged urine sample often renders it unsuitable for reliable analysis.
Such a sample frequently yields an “invalid” or “unsuitable” result, meaning the laboratory cannot confidently interpret drug presence or absence. An altered sample, whether due to degradation or contamination, can also be interpreted as an attempt to manipulate or tamper with the sample.
Lab Methods for Detecting Altered Samples
Drug testing laboratories employ various methods to assess the integrity of a urine sample upon receipt. An immediate temperature check is performed, typically within minutes of collection, to ensure the sample is within the expected body temperature range, usually 90-100°F (32-38°C). A deviation often signals the sample was not freshly provided.
Laboratories also measure urine specific gravity, which indicates its concentration. An old or excessively diluted sample may exhibit abnormal values, typically outside the normal range of 1.003 to 1.030. Creatinine levels are another integrity check; low concentrations, generally below 20 mg/dL, can indicate dilution or degradation.
The urine’s pH level is also assessed to ensure it falls within the expected physiological range, typically 4.5-8.0. Deviations can suggest adulteration or bacterial degradation. A visual inspection notes any unusual color, cloudiness, presence of sediment, or abnormal odor. Some laboratories also screen for common adulterants like nitrites, glutaraldehyde, or oxidants, which are used to mask drug use and indicate an invalid sample.
Outcomes of Submitting an Invalid Sample
If a urine sample is determined to be invalid or unsuitable due to its age or alteration, the most common outcome is a requirement for a new, fresh sample. This retesting ensures reliable analysis. The initial invalid submission does not automatically lead to a failed test but rather an uninterpretable one.
Depending on the drug test’s context, submitting an invalid sample can have significant repercussions. In employment, it may lead to job offer withdrawal, disciplinary action, or termination. For legal situations, an invalid sample could result in penalties or legal complications.
An invalid sample, especially if it shows signs of deliberate alteration or tampering, may be treated as a refusal to cooperate with the testing process. This interpretation can lead to more severe consequences than a failed drug test, as it implies an intent to defraud the system.