Written and medically reviewed by Dr. Diane Mueller, ND, LAc, DAOM, founder of MyLymeDoc. Last reviewed September 10, 2026.
If you have been unwell in a building you suspect, you want to know whether a test will finally give you an answer. Here is the honest version.
A urine mycotoxin test measures mold toxins and their breakdown products in a urine sample, and it is not an FDA-approved way to diagnose any illness. The CDC states plainly that “there is no FDA-approved test for mycotoxins in human urine” and that “mycotoxin levels that predict disease have not been established.” The same report goes further: urine mycotoxin tests “are not approved by FDA for accuracy or for clinical use.” A positive result also does not, by itself, mean your house is making you sick, because mycotoxins occur in ordinary food and hence appear in the urine of healthy people. What the test can do is add one measurement to a clinical picture that already includes your exposure history, your symptoms, and your building. Used that way it is useful. Used as a standalone verdict it is not, and this page is about telling those two situations apart.
The honest version is more complicated than either the labs selling the test or the agencies dismissing it will tell you. If you have not yet ruled the building in or out, mold illness symptoms is the better place to start.
A mycotoxin is a toxic compound produced by certain molds. Some are produced by the water-damage molds found indoors, and many are also present at low levels in ordinary food, particularly grains.
It measures mycotoxins and their metabolites that your body has excreted, which reflects recent exposure rather than a stored body burden. Mycotoxins are small toxic compounds produced by certain molds, and some of them are processed by the liver and cleared through the kidneys.
This matters for how you read the result. The test is a snapshot of what your body was clearing around the time you collected the sample. It is not a measurement of how much mold is stored in your tissues, and no test currently available to patients measures that. Anyone describing a urine panel as a “total body burden” is describing something the assay does not do.
Panels typically look for the same families of compounds: ochratoxin A, the aflatoxins, macrocyclic trichothecenes, gliotoxin, zearalenone, and in some cases citrinin and enniatin B. Those appear across most of the presentations clinicians see, though the presence of a compound in a panel says nothing about whether it is driving anyone’s symptoms.
RealTime Laboratories and Mosaic Diagnostics, the two labs cited in Google’s own AI Overview for this query, use fundamentally different detection chemistry, and they publicly contradict each other on how to handle urine dilution. No page selling either test explains this, and it is a common explanation for two conflicting results.
ELISA uses antibodies that bind to a target’s shape, which is fast and sensitive but can also bind compounds that merely resemble the target. LC-MS/MS, or mass spectrometry, identifies a molecule by its mass and the way it fragments, which is more specific.
Creatinine correction adjusts a urine result for how dilute the sample is, using a waste product the kidneys excrete at a fairly steady rate, so that drinking a lot of water does not make a result look artificially low.
| Feature | RealTime Laboratories | Mosaic Diagnostics |
|---|---|---|
| Method | Competitive ELISA, antibody-based | LC-MS/MS, mass spectrometry |
| Markers | 16 | 11 |
| Dilution control | First morning void | Creatinine correction |
| Listed price | $399 | Varies by practitioner |
RealTime describes its panel as screening “for 16 mycotoxins using competitive ELISA, a highly sensitive antibody-based detection method.” Mosaic states that its profile “utilizes state-of-the-art liquid chromatography tandem mass spectrometry (LC-MS/MS) technology to ensure high specificity.” Those are not two versions of the same test. Antibody assays detect a shape and can bind things that merely resemble the target; mass spectrometry identifies a molecule by its mass and fragmentation pattern.
The disagreement gets sharper on dilution. Mosaic says it uses “creatinine correction to ensure accurate and reliable results,” the standard approach for adjusting a urine measurement for how much water someone drank. RealTime says the opposite, warning that “normalizing mycotoxin results to creatinine may mask elevated toxin levels,” and controls dilution by requiring a first morning sample instead. Two respected labs, opposite methods, and a patient who runs both may reasonably receive two different answers about the same body.
A published critique of commercial mycotoxin testing comes from researchers who built much of mold illness medicine, not from skeptics outside it. This is worth knowing because the debate is usually framed as believers against deniers, and that framing is wrong.
In a review of mycotoxin testing pitfalls, Ritchie Shoemaker and colleagues report antibody assays with “monoclonal antibody specificity ranging from 2% to 11%” and conclude that “cross-reactivity rates of this magnitude are highly problematic.” They also argue that the fix is itself unreliable, noting that “different studies employ variable creatinine-based adjustments to account for urine dilution, thereby introducing additional sources of analytical variability.” Their recommendation is direct: “practitioners should exercise substantial skepticism regarding commercial mycotoxin testing that claims to establish clinically significant exposure.”
That assessment is not a reason to conclude mold illness is not real. CIRS is a recognized clinical picture with a substantial literature behind it. It is a reason to be careful about what any single urine panel can carry on its own.
Mycotoxins are in the ordinary food supply, especially grains, which is why healthy people with no mold exposure test positive. This is the confounder that makes a bare positive result difficult to interpret, and it has now been quantified.
A 2024 study measuring mycotoxins in the urine of UK children found that deoxynivalenol, usually shortened to DON, was the most prevalent mycotoxin detected. It appeared in “95.61% of samples above the limit of detection,” followed by OTA, ZEN and HT-2 toxin. The authors noted that “cereal foods contribute strongly to exposure.” These were ordinary children, not a water-damaged-building cohort.
The CDC makes the same point from the public health side: “low levels of mycotoxins are found in many foods; therefore, mycotoxins are found in the urine of healthy persons.” So the question a result has to answer is never “is anything detectable.” It is whether the pattern and the levels are meaningfully beyond what diet explains, and because no validated disease threshold exists, that judgment is clinical rather than automatic.
Provoking with glutathione or a sauna before collection is not part of any validated collection procedure, and it moves your sample outside the conditions the test was validated under. In our practice this is one of the most common questions patients bring in about mold testing.
US BioTek addresses the question directly in writing, which is unusual. It states that the company has “not issued provocation instructions with our kits or as standard practitioner instructions because this is a clinical decision,” and that its assay is “fully validated to random urine and does not require enhancement for accuracy.” The same page then goes on to describe a provocation regimen for clinicians who choose to use one, while stating that the decision is a clinical judgment rather than a validated step. We do not reproduce that regimen here.
Read that carefully, because it is the important part. The validation work behind these assays was done on unprovoked samples. When a provoked sample comes back higher, there is no validated reference range for what that number means. You will also see a widely repeated claim that glutathione interferes with mass spectrometry detection. We could not verify that mechanism against a primary source, so this page does not assert it.
Urine measures the person and ERMI or HERTSMI measures the building, and neither substitutes for the other. In our practice patients routinely choose one when the clinical question requires the other.
ERMI and HERTSMI are dust tests that score a building rather than a person. HERTSMI is a shorter version used to judge whether a building’s mold levels are safe for someone who is already sensitized.
Environmental testing answers a question urine cannot: is there a water-damage mold problem in this specific structure. The ERMI, as the ERMI literature describes, “provides a metric for the relative amount of mold due to water damage compared to other ubiquitous molds.” Its limits are equally clear, and the same paper notes that children in that study “do not spend all of their time in the bedroom and living room or even in their own home,” so one home’s score can miss the exposure that matters.
We could not locate any published study comparing urine mycotoxin levels against ERMI or HERTSMI scores in the same subjects. That absence is worth stating plainly rather than papering over, because it means nobody can currently tell you how a urine number should track against a building score.
If your central question is whether your house is the problem, ERMI testing answers it more directly and usually for less money.
The clinical case rests largely on one 2013 study, and that study used the antibody method the critics object to. Presenting this honestly is the only way to let you weigh it yourself.
Brewer and colleagues tested patients with chronic fatiguing illness and reported that “urine specimens from 104 of 112 patients (93%) were positive for at least one mycotoxin,” with ochratoxin A in 83% and macrocyclic trichothecenes in 44%. They also reported that “exposure histories indicated current and/or past exposure to WDB [water-damaged buildings] in over 90% of cases,” which is the strongest argument against pure dietary confounding. The methods section states the work used “competitive direct enzyme linked immunosorbant assays.” So the foundational pro-testing evidence and the principal methodological criticism are aimed at the same assay.
There is one genuinely validated method, and its purpose is narrower than patients assume. A 2025 analytical method published for occupational biomonitoring covers aflatoxins, ochratoxin A, gliotoxin and citrinin in urine by LC-MS/MS. It was developed and verified by a working group on analyses in biological materials, which establishes that the chemistry can be done rigorously. It validates measurement, not diagnosis.
RealTime lists its mycotoxin panel at $399, and a urine mycotoxin test is usually an out-of-pocket cost. Mosaic and US BioTek price through practitioners and do not publish a list price, so ask before you order.
Coverage for laboratory-developed tests varies by plan and is often denied. Call your plan with the CPT code the lab provides before you order, and ask whether your HSA or FSA will accept the charge. Ask about the cost of a repeat test too, because a single urine mycotoxin test rarely settles anything on its own and retesting after remediation is common.
Order it when the result would change what you do next, and skip it when it would not. That single rule resolves most of the confusion.
Order a urine mycotoxin test if all three of these are true:
Skip it, for now, if any of these is true:
Sequencing matters more than the panel itself, and our guide to binders for mold detox covers why order of operations decides the outcome.
In our practice we look at the building, the timeline, and the whole clinical picture before deciding whether a urine panel adds anything, and we treat the terrain before chasing any organism. If a result would not change the plan, we say so rather than sell the test. If you want help deciding whether this is the right next step for your situation, book a consultation and bring whatever testing you already have.
It depends what you mean by accurate. The mass spectrometry chemistry can identify compounds reliably. What has not been established is a level that predicts illness, which is why the CDC states that “mycotoxin levels that predict disease have not been established.” The measurement can be sound while its meaning remains uncertain.
Some labs sell directly to consumers and others require a practitioner to order and receive results. The harder problem is not ordering it but interpreting it, since there is no validated cutoff separating a sick person from a healthy one.
No. Mycotoxins appear in the urine of healthy people because they are present in ordinary foods, particularly grains. A positive result is one data point that has to be read alongside your exposure history, your symptoms, and ideally testing of the building itself.
Usually not. These are laboratory-developed tests without FDA approval for diagnosing disease, and coverage varies by plan. Call your plan with the CPT code the lab provides before ordering, and ask whether your HSA or FSA will accept the charge.
Some labs sell direct to consumers and others require a practitioner to order it and receive the results. Buying it is the easy part. The difficulty is that no validated cutoff exists to tell you what your number means, which is why the result is worth little without someone to read it against your history.
They answer different questions. Urine panels look for the toxins themselves, while blood testing for mold illness generally looks at the body’s inflammatory response markers. Neither is a standalone diagnostic, and which one is useful depends on what question you are trying to answer.
The first step is removing ongoing exposure, because no binder or detox protocol works while you are still living in the source. Confirm whether the building is actually the problem, then work with a clinician on a sequenced plan. Treating a lab number without addressing the environment is a common way this goes wrong.
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