Why Creatinine Levels Matter for Urine Drug Testing

August 18, 2023by Jerald Mackey12

Creatinine is an important component of urine drug testing. Tracking creatinine levels can enable treatment centers to fine-tune treatment plans and alert staff to clients who are trying to rig the system.

What is Creatinine and Why Does It Matter?

Creatinine is a waste product that is produced during muscle metabolism and is excreted through the kidneys. It is a reliable indicator of the body’s muscle mass and overall kidney function.

Because creatinine is produced at a relatively constant rate and is filtered by the kidneys, its concentration in urine should be consistent over time. This consistency makes creatinine an essential reference point in urine drug testing—and one on which Valley Medical Laboratory focuses.

Using Creatinine to Identify Urine Tampering

Measuring creatinine levels helps detect attempts to dilute or manipulate urine samples. Some individuals attempt to mask the presence of drugs in their system by consuming excessive amounts of water or other liquids before a urine test. This can lower the concentration of drugs and their metabolites in the urine, thus affecting the accuracy of the toxicology testing results.

What these individuals don’t realize, however, is that creatinine levels can help identify any attempts at urine dilution. That’s because diluting the urine in this fashion impacts the creatinine concentration. When a sample is diluted, the creatinine levels become abnormally low. When we find abnormally low levels of creatinine in a client’s urine, that suggests that the sample may have been tampered with, affecting the test results for other substances.

For these reasons, our reference lab compares the concentration of creatinine in each urine sample to typical ranges. If the creatinine level is within the expected range, it suggests that the sample is not diluted or tampered with, ensuring the accuracy of drug test results. If the creatinine level is not within range, providers are alerted and further testing may be necessary.

Other Factors That Might Contribute to Abnormal Creatinine Levels

Low creatinine levels are indicative but not determinative of urine tampering. There are several other factors that can contribute to unusual levels of creatinine in a person’s urine, including:

  • Kidney disease typically results in elevated creatinine levels
  • Muscle disorders can result in reduced creatinine production
  • Interaction with certain medications can influence creatinine production and excretion

Providers analyzing testing results need to take these medical considerations into account. Properly interpreting results requires skilled interpretation of the individual’s medical history and underlying health conditions.

Valley Medical Laboratory Standardizes Test Results to Creatinine Levels

At Valley Medical, we realize that creatinine is an integral component of urine drug testing, serving as a valuable indicator of sample integrity and dilution attempts. We go beyond simply measuring creatinine levels to standardizing all test results to the creatinine levels in the client’s urine.

By correlating creatinine levels with drug levels, our testing can accurately determine if the urine sample has been diluted. This identifies any attempt by clients to artificially dilute their samples to mask drug use.

Standardizing the client’s results for the amount of creatinine present provides a more accurate assessment of substances present in the client’s body. Most reference labs do not standardize to creatinine levels, which can potentially lead to misleading results and missed treatment opportunities.

This creatinine standardization is just one unique aspect of Valley Medical’s toxicology testing services. We also offer vTOX® DNA verification that eliminates the need for viewed urine collection. For these and other reasons, treatment centers across the state of Minnesota rely on Valley Medical for fast, accurate, and easy to use toxicology testing.

Click here to learn more about vTOX urine drug testing at Valley Medical Laboratory—complete with DNA verification.


Jerald Mackey


  • Rhonda

    May 11, 2024 at 8:03 pm

    Determining someone’s fate on the levels of creatine in their test is not only ignorant but way off base. Of being watched to take your test no way to dilute it you say drinking too much water is a cause of low creatine levels in urine where is the info on how much water you may consume. Did you ever think maybe they are just thirsty or want to make sure they can pee when they get there? So what do you flag if it’s too high? Better drugs? Less water? How about Lupus kidney failure pretty much any autoimmune disease and some cardio diseases as well. Stop messing with people’s lives and lives of their family just stick to the facts when these levels were low did they have any drugs in them at all? I’m guessing no play by the rules people and mind your own


    • Michael Miller

      May 13, 2024 at 2:34 pm

      As noted, creatinine level is just one indicator of possible urine tampering. Also as noted, creatinine levels can be affected by other factors. It should not be the only indicator of urine tampering.


  • Sherilee Donison

    February 3, 2024 at 1:46 pm

    Hi there what would cause my levels to be extremely high. Normally in random tests they’ve been 5-8 the last 2 have been 17 and 12!! I’m always positive for amphetamine due to my adhd medication of vyvanse and ephedrine pseudo ephedrine (allergy medication and possibly my bupropion? But now positive for methamphetamine?? What’s going on here? My Dr is treating me like a different person after 13 years and feel disgusted


    • Michael Miller

      February 5, 2024 at 2:49 pm

      There can be many causes of high creatinine levels. These include:

        Infection in kidney
        Impairments of kidney functions
        Doing strenuous exercises in excess
        Consumption of protein and meat excessively
        Specific foods and supplements can increase creatinine levels
        Drug use
        Certain specific medication
        Sudden shock
        Excessive blood loss
        Autoimmune disorders
        Urinary tract infections
        High blood pressure
        Abnormal muscle breakdown
        Diabetes mellitus

      You should probably consult with your physician to determine what might be causing your creatinine levels to increase in the manner you described.


  • Jamie

    February 1, 2024 at 1:21 pm

    The MRO wants articles with peer backed support on what can explain low levels of creatinine if not an illness and I can find absolutely nothing about it, I’ve read plenty that mention medications can cause this but very little information on this. Are there any in depth studies I can provide to the MRO about the medications that are most likely to cause erroneous results or interference causing erroneous results that I can send to this doctor?


    • Michael Miller

      February 5, 2024 at 2:45 pm

      There are certainly classes of medication that can cause lower creatinine levels, such as diuretics. Unfortunately, we don’t handily have literature to support this. However, we know physiologically that diuretics cause a person to have more diluted and more frequent urine, which would lower their creatinine levels on urine testing. I’m not sure we can provide any more information than this.


  • Calvin

    January 31, 2024 at 1:38 am

    I take creatine for weight lifting purposes not because I want to try to beat a drug test. If I take regular creatine monohydrate as recommended on the bottle the lab would still be able to test me for drug abuse right? And the test would still be accurate. The reason I ask is because I’m on sublacade and I’ve lost alot of weight, muscle strength and mass not to mention energy which all of which creatine will help with till this sublacade is completely out of my system. I’m in a halfway house and we r not allowed to take creatine because staff thinks we are using it to pass drug test ??????


    • Michael Miller

      January 31, 2024 at 9:45 am

      Calvin, thanks for writing. Don’t confuse creatine, which you take for weight lifting purposes, with creatinine, which is a chemical byproduct of creatine produced by the kidneys and used by some labs (including ours) for urine validity testing. In any case, you’ll need to follow the rules of your halfway house; if, for whatever reason, they ban creatine, you’ll have to discuss it with them.


  • Uly

    November 28, 2023 at 3:56 pm

    I don’t understand this testing method of testing your creatine levels.. My dr said my urine came out diluted like if I poured water in my urine and diluted it. I haven’t done any drugs for decades and I’m being accused of tampering with my drug test. Hows that?


    • Michael Miller

      November 28, 2023 at 4:25 pm

      We test creatinine levels on every urine sample as part of our validity testing. Low levels do not mean that urine has been tampered with necessarily, as there are several reasons a person could have low levels. It is ok to discuss this further with your provider to help explore a reasonable explanation for low levels if you know you haven’t tampered with your urine sample. If a provider questions you about your sample, that doesn’t mean you are being accused of tampering; instead, your provider is inquiring to see if one of those other reasonable explanations is likely.


      • Jamie Russell

        January 17, 2024 at 3:15 am

        I am absolutely being accused and my oncologist and family doctor told me that 2 of my medications are causing the problem and the MRO wants to interpret this differently. My doctor says that an interpretation of something is basically an option more or less. The MRO asked me to have my doctor provide a list of medications in a report with peer backed support and research to prove that medication can cause creatinine levels to be too low, my doctor said he graduated medical school and he wasn’t a professor either, so I’m stuck in the middle with no where to go. I can’t find anything really on the Internet and can’t understand most of what I read because I am NOT a doctor. I have been completely destroyed by this including losing my job of 24 years. I am a stage 3 breast cancer survivor and going through a divorce and now this disturbing absolutely erroneous accusation has caused me to just give up because I can’t understand how a MRO is even allowed to say that my doctors are basically dumb. This has most likely destroyed people’s life other than just me. It’s just wrong.


        • Michael Miller

          January 26, 2024 at 10:14 am

          We are sorry to hear about your situation. This sounds like an issue that needs be resolved between your doctor and the MRO. Many companies have a process for protesting MRO decisions like this, you should consult with your HR department for next steps. As we’ve noted, low creatinine levels do not necessarily mean that urine has been tampered with, as there are several factors that could cause a person to have low levels.


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