How We Test for Mold Exposure
The VCS Test and Urine Mycotoxin Testing
When patients come to me with concerns about mold exposure, two tools come up often: the Visual Contrast Sensitivity test and urine mycotoxin testing. Here's how each one actually works, what the results look like, and how they typically factor into a care plan.
The Visual Contrast Sensitivity test, or VCS test, measures a neurologic function of vision called contrast sensitivity — your ability to distinguish subtle differences between light and dark. The test presents a series of patterns on a screen at progressively lower contrast levels, similar in concept to a hearing test where tones get quieter as the exam progresses. Each eye is tested separately, at a fixed distance from the screen and under consistent lighting, since both distance and lighting affect the outcome. As the patterns become fainter, you identify what you can still see; the point at which you can no longer reliably detect the pattern becomes your contrast sensitivity threshold. That threshold is then compared against established reference curves to produce a pass or fail result for each eye. The test itself takes about ten to fifteen minutes and results are available immediately.
Urine mycotoxin testing works differently: it's a direct laboratory measurement rather than a functional screen. A urine sample is sent to a specialty lab such as Doctor’s Data or MycoTOX by Mosaic Diagnostics. Doctor's Data is one of the more commonly used labs for this — where it's analyzed for specific mycotoxin compounds, such as ochratoxin A, trichothecenes, aflatoxins, and gliotoxin, depending on the panel ordered. The lab report comes back with a concentration for each mycotoxin tested, typically expressed in nanograms per milliliter or parts per billion, along with a reference range indicating whether that concentration falls within, above, or below the lab's defined threshold. Because mycotoxins are processed and cleared by the body over time, the sample reflects a window of relatively recent exposure rather than a lifetime total.
When it comes to building a care plan, I typically use these two tools alongside each other and alongside the patient's symptom history and any information available about their home or work environment. A VCS result, whether pass or fail, becomes one data point that helps direct next steps — for instance, whether to move forward with mycotoxin testing at all, or to pursue further neurological or immune workup. A urine mycotoxin panel then adds specificity, showing which particular compounds are elevated, which can inform which binding agents or detoxification support a treatment plan will emphasize. From there, a typical plan often includes environmental steps to reduce ongoing exposure, targeted supplementation or binders matched to the mycotoxins identified, and periodic re-testing — often with VCS retesting to track functional improvement, and repeat urine mycotoxin testing every few months to monitor whether levels are trending down as treatment progresses.
If you're curious whether this kind of testing makes sense for your situation, that's exactly the kind of conversation I'm happy to walk through with you in a telemedicine visit.
This post is for general educational purposes and reflects my own clinical perspective on mold and biotoxin testing. It isn't intended to diagnose any individual condition or replace a personalized medical evaluation.
Dr. Evelyn Cordova | Telemedicine Naturopath