Last updated: November 27, 2023
The accurate interpretation of employee drug tests is not always straightforward. Drug abusers try lots of ways to “beat” the test so their drug abuse goes undetected. However, that’s been going on since drug testing began and lab techs are on to their trickery. A little-known factor called specific gravity can dash a cheater’s hope to fly under the radar.
Urine drug tests are a common tool used by employers, doctors, and law enforcement to detect the presence of illicit substances in a person’s system. These tests work by analyzing a sample of urine for the presence of certain drugs or their metabolites. Specific gravity is a measure of how concentrated a urine sample is compared to pure water. It’s calculated by dividing the density of the urine by the density of water. This number provides important information about the urine sample, such as whether it is too diluted or too concentrated.
Is it high or low?
In short, a low specific gravity means the urine is diluted, while a high specific gravity signifies concentrated urine. The concentration of urine can be influenced by various factors such as fluid intake, dehydration, and kidney function.
In the context of urine drug testing, the specific gravity of urine is critical as it affects the concentration of drug metabolites in the sample. Drug metabolites are the byproducts of drug metabolism that are eliminated from the body through urine. The concentration of drug metabolites in urine can vary depending on various factors such as the dose, route of administration, frequency of use, and individual metabolism.
However, one critical factor affecting the concentration of drug metabolites in urine is the specific gravity of the sample. If urine is diluted, drug metabolites will be more diluted which makes them more difficult to detect in the sample. On the other hand, if the urine is concentrated, the concentration of drug metabolites can be higher, making it easier to detect them during the drug test.
As a result, urine with low specific gravity may sometimes result in false-negative drug test results as small amounts of drug metabolites may not be detectable. Urine with high specific gravity may sometimes result in false-positive drug test results, indicating drug use even when the person is not under the influence of any drug.
Cut-off levels for determination
The trigger for conducting the specific gravity test during a drug test analysis is whether or not the creatinine level in urine is off kelter. Creatinine is a waste product that the body produces from normal wear and tear on the muscles. It’s the result of the breakdown of creatine, an amino acid.
The levels fluctuate depending on such things as age, race, gender, and body size. A low creatinine level indicates that urine is diluted. It’s a red flag that goes up immediately during a drug test analysis. The normal range is between 20 and 400 milligrams per deciliter (mg/dL). If the creatinine level is between 2 and 20 mg/dL, the urine is diluted.
Testing facilities use the specific gravity measurement of urine samples to interpret the results. Urine samples with a specific gravity of less than 1.003 or higher than 1.033 are considered adulterated, and the results are not accepted. This is because such specific gravity measurements indicate that the sample is either too diluted or too concentrated. This can significantly affect the accuracy of drug test results.
It could be unintentional
Just because a urine analysis proves to be diluted, it doesn’t necessarily indicate that the person was trying to mask drug use. Some people naturally drink lots of water to stay healthy. Others—especially if they suffer from shy bladder syndrome—may have been trying to ensure they can give a urine sample when requested to do so. Lastly, we’ll note that certain medications or kidney problems cause urine dilution.
Here are some tips to provide prior to a drug test. They can prevent your employees from obtaining an inconclusive result because the specimen was diluted:
- Limit their fluid intake before the test
- Avoid diuretics, like coffee and tea, for example prior to the test
- Report for the test early in the morning
If your employees require frequent hydration throughout the day, as in the construction industry, for instance, collect the urine sample before work.
The specific gravity of urine is a critical factor affecting the accuracy of urine drug test results. Testing facilities should adhere to strict specific gravity cutoff values. It ensures that the results of the test are accurate and reliable.
Should an employee receive an inconclusive result related to specific gravity, follow the procedure outlined in your drug-free policy specifically from that point forward. It helps ensure you have the leg you need to stand on should a disgruntled employee try to drag you into court down the road.