The experience of being asked to retake an employment drug test can generate significant concern for the job candidate or current employee. Being called back for a second collection does not automatically indicate a positive result from the initial sample. A retake is typically required because the first specimen yielded an “invalid,” “canceled,” or “inconclusive” result. These outcomes mean the laboratory could not definitively confirm the sample’s integrity or analyze it to the required legal or administrative standard. Retests are triggered by procedural failures, issues with the sample’s biological consistency, or technical problems within the testing facility.
Administrative and Chain of Custody Errors
Failures in the procedural handling of the sample, occurring outside of the laboratory’s analytical testing, are a major cause of invalidation. These issues frequently revolve around the Chain of Custody (COC) process, a stringent protocol designed to document every transfer of the sample. A break in the COC renders the specimen legally invalid because its integrity cannot be guaranteed.
Incomplete or inaccurately transcribed paperwork is a common administrative failure necessitating a retake. If the donor’s name, the collector’s signature, or the date and time of collection are missing or inconsistent, the lab cannot proceed with analysis. Likewise, if the security seal placed over the sample container is damaged, improperly applied, or missing an identification number, the sample must be rejected.
The integrity of the sample during transport can also lead to a required retest, even if the collection was flawless. If the sample is physically damaged, spilled, or exposed to temperature extremes during shipping, the laboratory will cancel the test result. These handling failures mean the original specimen is unsuitable for analysis, forcing the employer to request a fresh collection.
Sample Validity and Integrity Issues
Laboratories perform sophisticated validity testing on every specimen to confirm it is human urine and has not been tampered with. This analysis checks for physiological markers like creatinine, specific gravity, and pH levels, which must fall within established norms. When these markers deviate significantly, the result is categorized as invalid, suggestive of substitution or adulteration, leading to a mandatory retest.
Temperature Readings Outside Acceptable Range
The collector checks the temperature of the urine sample immediately after it is provided, typically within four minutes of collection. This check is a preliminary screen to detect substitution, as a freshly voided sample should align closely with the human body’s core temperature. The acceptable temperature range is tightly controlled, generally required to be between 90°F and 100°F (32°C to 38°C).
A temperature reading outside this narrow window suggests the specimen was stored externally, such as synthetic urine or a pre-collected sample. If the temperature is too high or too low, the collector must record the discrepancy and often perform a new collection immediately under direct observation. The temperature failure itself is a strong indicator of an attempt to manipulate the result, leading to an invalid test.
Diluted or Substituted Samples
A diluted sample contains an unusually high amount of water, which lowers the concentration of drug metabolites and potentially masks drug use. Laboratories detect dilution by measuring creatinine and specific gravity. Creatinine is a waste product of muscle metabolism, and a level below 20 mg/dL, combined with a specific gravity between 1.0010 and 1.0030, is typically defined as dilute according to federal guidelines.
A substituted sample is not human urine, such as water, apple juice, or synthetic urine. If the creatinine level falls below 2 mg/dL, it is considered physiologically impossible for human urine and is often grounds for immediate cancellation and a supervised retest. Many employer or Department of Transportation (DOT) policies require a mandatory retest for a diluted result, as the low concentration prevents a definitive negative finding.
Adulteration or Tampering
Adulteration involves adding a foreign chemical substance to the urine specimen to interfere with the drug testing assay. These substances are designed to destroy or chemically alter the drug metabolites. Common adulterants include household products like bleach, laundry detergent, vinegar, or specialized commercial products containing nitrites or glutaraldehyde.
The laboratory’s validity testing screens for the presence of these oxidizing agents and checks the sample’s pH level. A pH level outside the normal range of 4.6 to 8.0, or the presence of an oxidant, signals chemical tampering. Detection of an adulterant results in immediate invalidation of the test, requiring the employer to mandate a new, often observed, collection.
Technical Laboratory Processing Problems
Even if the specimen is collected perfectly, problems can still arise once it reaches the testing facility, necessitating a retake. These issues relate specifically to the analysis phase and involve instrumentation failures, calibration errors, or human procedural mistakes during screening or confirmation stages.
Equipment malfunctions, such as inconsistent readings from a spectrophotometer or improper calibration of a mass spectrometer, can cause a test result to be canceled. A lab must demonstrate the reliability of its instruments; any documented lapse in quality control can lead to the invalidation of all samples processed during that period. The employer is then notified that the result is canceled due to a technical error, triggering a retest.
A frequent reason for an inconclusive result is insufficient sample volume to complete the full testing protocol. The initial screening test, often an immunoassay, may yield a result close to the cutoff threshold, requiring a confirmation test like Gas Chromatography/Mass Spectrometry (GC/MS). If the original volume was too low to perform this necessary secondary confirmation, the test is reported as inconclusive. Without the definitive confirmation result, the Medical Review Officer (MRO) cannot legally verify a positive or negative finding, and a fresh, adequate sample is required.
Employer and Regulatory Mandates
A request for a retest can be independent of the first test’s result or any procedural error, driven purely by policy or legal requirements. These mandates are established by the employer’s internal drug-free workplace policy or by federal and state regulations. The initial sample may have been perfectly valid, but the circumstances surrounding the donor’s employment status or history trigger an automatic subsequent test.
An employee who has previously violated a drug policy and completed a rehabilitation program is often subject to follow-up testing. This follow-up testing is a policy-driven mandate, meaning the employee must submit to a new, often random, test regardless of the first test’s clean result. Companies may also institute a program of random testing where employees are selected periodically by a computer-generated process.
A retest may also be required if a company decides to change its testing methodology for a particular employee or group. An employer might initially use a urine test but then mandate a move to hair follicle testing or oral fluid testing for a different drug panel. This change in testing scope makes the original test result irrelevant to the requirement for a fresh collection.
Preparing for the Retest
When preparing for a mandated retest, the focus should be on ensuring the collection process is compliant and stress-free. The most practical advice is to manage hydration levels carefully in the hours leading up to the test to prevent a second dilute result. Excessive fluid consumption or using diuretics should be avoided to ensure the urine’s specific gravity and creatinine levels are within the normal physiological range.
The donor must be meticulous in observing the administrative steps during the collection process to prevent a chain of custody error. This involves confirming that the collector correctly seals the sample containers and that the identifying information on the paperwork matches the labels on the specimen bottles. Following the collector’s instructions precisely during the collection phase is also important to avoid issues with temperature or timing.
Minimizing stress and anxiety is helpful, as a retest implies a failure of the process or the sample itself, not automatic guilt. The goal is to provide a sufficient quantity of unadulterated, fresh human urine within the required temperature range. Paying close attention to these procedural and biological details helps ensure the second test yields a conclusive and final result.