Urine Mycotoxin Testing: What It Actually Measures
Urine mycotoxin testing directly measures the mycotoxins themselves (or their metabolites), NOT antibodies, using liquid chromatography-tandem mass spectrometry (LC-MS/MS) as the analytical method. 1, 2
Analytical Method and Detection
The standard approach for urinary mycotoxin testing employs LC-MS/MS (liquid chromatography-tandem mass spectrometry) combined with stable-isotope dilution assay (SIDA) to directly quantify mycotoxins and their metabolites at picogram per milliliter (pg/mL) concentrations. 1
Key Technical Details:
Sample preparation typically includes enzymatic cleavage of glucuronic acid conjugates (since many mycotoxins are excreted as glucuronide conjugates) followed by extraction and concentration. 2
Detection limits are extremely sensitive, ranging from pg/mL to ng/mL levels, allowing measurement of very low concentrations of actual toxin molecules. 1, 2
Multiple reaction monitoring (MRM) transitions are used for unambiguous identification and quantification of specific mycotoxins. 1
What Is Actually Being Measured
The tests detect and quantify:
Parent mycotoxins excreted unchanged in urine (e.g., ochratoxin A, fumonisin B1, aflatoxin M1). 1, 3
Metabolites of mycotoxins produced by human metabolism (e.g., deoxynivalenol-glucuronide, de-epoxydeoxynivalenol, α-zearalenol, dihydrocitrinone). 2, 3, 4
Both free and conjugated forms after enzymatic treatment to release glucuronide-bound toxins. 2
Critical Distinction from Fungal Antigen Testing
This is fundamentally different from fungal infection testing discussed in the American Thoracic Society guidelines. 5
Fungal Infection Testing (Different Context):
Urinary antigen tests for fungal infections (Histoplasma, Blastomyces, Coccidioides) detect fungal polysaccharide antigens, not antibodies. 5
Serum antibody tests measure the immune response to fungal infections and can cross-react with other endemic mycoses. 5
These tests are for diagnosing active fungal infections, not mycotoxin exposure. 6
Mycotoxin Exposure Testing (Your Question):
Direct chemical analysis of toxin molecules using mass spectrometry. 1, 2, 7
No immunological component—purely analytical chemistry measuring actual toxin concentrations. 1
Common Pitfalls
Do not confuse mycotoxin testing with fungal infection testing. Mycotoxins are toxic chemical compounds produced by molds in food, while fungal antigens and antibodies relate to active infections with pathogenic fungi. 1, 3
Sample preparation is critical. Without enzymatic deconjugation, glucuronide-bound mycotoxins will be missed, underestimating total exposure. 2
Creatinine normalization is often used to account for urine dilution when interpreting results and estimating daily intake. 7