Last updated : December 16, 2024
If someone receives a negative dilute result on their drug test, it doesn’t mean they “pass” it. While that last cup of coffee or glass of water doesn’t adversely affect a urine drug test, consuming large quantities of fluid before the test may, but not in the way some people believe.
One of the most common myths about drug testing is that flushing your system with excess fluids hides or masks drug use long enough to submit a specimen that won’t contain any drug metabolites. Not true. Drug metabolites—the biological byproducts of drug use—will still show up in a test sample. Moreover, consuming excess fluids will cause your body’s creatinine levels to rise above normal.
And, just for the record, consuming large quantities of fluid doesn’t affect mouth swab or hair follicle drug tests either.
Raising a red flag
Creatinine levels that are out of the normal range may indicate that someone attempted to hide or mask drug use. When drug metabolites aren’t detected in the specimen but creatinine levels are out of the normal range, it’s determined to be inconclusive. The breakdown reads as “negative dilute.” That means creatinine levels indicate there is too much water in the urine. A diluted urine sample is a sign of someone trying to mask drug use. Even though there are no drugs detected, the fact that the urine is diluted poses a problem.
A positive dilute drug test result occurs when creatinine levels are outside of the normal range and drug metabolites are detected. A positive dilute is always considered positive and will result in termination if conducted under a program for federal employees or a DOT drug test. That’s often the case for those employed in the general workforce too.
If the result is a negative dilute, many drug testing policies will require employees to return for another drug test. And, it’s often set up to be observed.
Where DOT regulations rule
A specimen with creatinine levels (a waste product in the blood created by the normal use of muscle cells) of greater than or equal to 2 mg/dl but less than 5 mg/dl, and specific gravity less than or equal to 1.0010 calls for the Medical Review Officer (MRO) to require the donor to return for a second drug test under direct observation.
The second test following a negative dilute report must render a negative result. An applicant with a second directly observed negative dilute urine test result will be removed from duty or, in the case of a pre-employment test, isn’t eligible for hire under the employer’s uniformly enforced policy.
Should the employee decline a required retest due to a dilute specimen, it will be considered a “refusal to be tested.” These are treated as a confirmed and verified positive result. The offer of employment is rescinded or current employment is terminated.
Where the employer decides
Non-DOT and DOT regulations under 49 CFR Part 40.197 allow the employer to decide for himself whether to have the donor return for another one-time collection ensuring the following:
- The employer has a policy statement in writing before the fact that allows the practice.
- All employees are treated equally.
- The recollections are not observed recollections.
- Only one recollection is allowed; the result of the second collection is the result listed, even if another negative dilute.
- The decision to re-collect may vary by the reason for the testing; i.e., an employer may decide to re-collect all pre-employment dilute negatives, but not random dilutes, or vice versa.
In the event of a negative result when a specimen produces creatinine levels of 5 mg/dl or greater, but less than 20 mg/dl, and the specimen’s specific gravity is greater than 1.0010 but less than 1.0200, the employer will follow their documented policy on how to handle the situation. When the lab report is negative dilute, the employer’s policy should be to either accept the result as is or have the donor return for a second collection.
As with a DOT drug test, when an employee declines a retest required due to a dilute specimen, it will typically be considered a “refusal to be tested.” Refusals to test are generally treated as a confirmed and verified positive result, and the offer of employment rescinded or current employment terminated. This, of course, must be specified in the company’s documented drug testing policy.
A policy statement must already be in place
Under both DOT and non-DOT drug testing programs, the decision for handling a negative dilute drug test result is up to the employer. The company should have a documented drug testing policy before conducting employee drug tests.
The only exception is when the specimen is out of range and the MRO requires a retest. This protects employers by eliminating the need to make arbitrary drug testing decisions in the heat of the moment.
In some cases, a negative dilute may be normal if the person normally consumes large amounts of water for health reasons. Or they may have done so on this one occasion out of concern for being able to produce a specimen. Policy statements can set those standards of action.
On the other hand, if the test result is a positive dilute, the “dilute” aspect is of minimal interest and the documented drug testing policy for a positive result must be followed.
Avoiding a negative dilute result
Once again, avoid consuming too much fluid before a drug test, and avoid too much caffeine or other diuretic intake, both of which can cause a negative dilute drug test result. Any attempt on an employee’s part to dilute the sample will likely be both identified and taken as an attempt to cheat on the test.
The best advice is to avoid excessive fluid and diuretics, and if possible, don’t urinate less than two hours before your drug test. Following that, don’t drink more than 24 oz of fluid.
This will help ensure you don’t produce a dilute drug test result.
