The urine drug test is one of the most common ways to screen for substance abuse, particularly in the workplace. Collecting a urine sample is quick and straightforward, but what happens if the test concludes with diluted results?
In this blog, learn what negative dilute is, what it can mean for the drug test results, and how this can be avoided during the drug testing process.
What is a Negative Dilute Drug Screen?
If a drug test result reads "negative dilute," it means two things:
The individual tested negative for drugs.
The urine specimen donor was excessively hydrated at the time they provided the urine sample. As a result, the urine specimen was diluted.
In addition to urine specimens being dilute, there might also be abnormal creatinine levels in the urine. Creatinine is a waste product that the body makes.
To check for dilute specimens, drug testing laboratories will often use a urine-specific gravity test. The specific gravity values tell them what the urine specimen is made of and in what concentration. That way, they can determine why the urine sample is diluted.
Learn more about the specific gravity of urine.
What is a Normal Specific Gravity?
Normal human urine is around 1.005 to 1.030, although it can go as low as 1.020. Specific gravity values lower than this could indicate an attempt at tampering with the urine sample or kidney issues. (More on this in a moment!)
Positive Dilute Drug Test Result
Even with the specific gravity values thrown off, drug testing can still pick up on substance use.
A positive dilute result means that the amount of water and the creatinine concentration were abnormal but the individual still tested positive for drugs.
Only a clear positive test result (or negative test result) can definitively say if drugs or alcohol were found in the individual's body.
Why Are Negative Dilute Results a Bad Thing?
A negative dilute drug test can't adequately determine the presence of drugs in the urine specimen. Thus, the drug test might produce false-negative results — even if that individual did consume drugs — warranting a re-test.
Note that negative dilute drug test results can happen for a couple of different reasons.
One possible explanation is that the donor made an attempt to cheat the test by intentionally drinking an excessive volume of fluids prior to testing. Some individuals do this to flush their systems as much as possible and hopefully make it harder for any illicit substances to be detected.
Also worth noting is that it is possible to unintentionally drink an excessive amount of water, thereby causing dilute specimens.
Another plausible cause is kidney problems. The kidneys help to remove waste from the body. However, if they're not functioning properly, they can release too much water through the urine. This can lead to a negative dilute drug test.
If this is the case, the donor of the urine sample should speak with their healthcare provider.
How to Avoid Negative Dilute Results in Drug Testing
To maintain a drug-free workplace, an employer might require pre-employment drug testing (as part of the hiring process), random testing, reasonable suspicion drug tests, post-accident screening, and return-to-duty drug testing, in line with company policy.
How can an employer avoid seeing a negative dilute specimen on a drug test?
Because urine specimens aren't typically collected under direct observation, this is where a medical review officer (MRO) comes in. An MRO can review the results of the employer's drug tests to determine the reason behind the negative dilute test result and the appropriate next steps.
For employees to avoid negative dilute results, it simply comes down to refraining from consuming too much water (or other liquids) in the hours leading up to getting drug tested. Staying hydrated is part of a healthy lifestyle, but how much water is "too much water?" The employee should stick to what they normally drink! A good rule of thumb is to check the color of their urine. If it's very pigmented, they're probably dehydrated. If it's a faint yellow, they're properly hydrated.
Should the individual still end up with a negative dilute test result, then they should speak with the medical review officer or their healthcare provider to determine if they might be dealing with kidney problems.
What Else Can Prevent Accurate Drug Test Results?
A dilute specimen isn't the only thing that can lead to inaccurate results and a second attempt at drug testing.
Certain prescription medications can trigger a false positive. For example, drugs like ibuprofen, naproxen, quinolones, trazodone, and nonprescription nasal inhalers have been known to trigger false positives for amphetamine, methamphetamine, methadone, opioids, PCP, barbiturates, benzodiazepines, and cannabinoids.
This is another instance when a medical review officer can validate the test results.
Maintain a Drug-Free Workplace With Ease
Drug testing for the workplace can feel overwhelming. Having a reliable screening partner helps ease the process.
US Drug Test Centers only partners with SAMHSA-certified laboratories. In addition, an MRO validates all test results to ensure accuracy.
This is how we can identify a negative dilute drug test result and decide the appropriate steps to take next — for example, if a second test is necessary. You can order a test for an individual substance, or opt for a panel test that screens for multiple substances.
Plus, you can choose a collection site from our 20,000+ locations around the nation. Most locations even accept same-day appointments.
Whether you're an employer or employee (or even a parent who wants to get their teenager screened), testing for illicit substances has never been more convenient. If you're ready to move forward, you can order a test online, find a location near you, or contact us with any questions.
Marquisha Blanche is the Director of Operations for US Drug Test Centers and has been working hard since 2018. 
