What does the Clostridioides difficile Toxin A (Enterotoxin) test measure?

Why is Clostridioides difficile Toxin A (Enterotoxin) measured?

Detection of Toxin A in stool confirms the presence of free active toxin — the direct mediator of colonic mucosal damage — in a symptomatic patient, supporting the diagnosis of Clostridioides difficile infection (CDI) requiring treatment. EIA-based toxin A detection has relatively low sensitivity (70–85%) compared to NAAT but high specificity — a positive EIA toxin A result in a patient with clinically significant diarrhoea is highly specific for active CDI. A negative toxin A EIA does not exclude CDI if toxin B or NAAT is not also tested, as approximately 3–5% of C. difficile strains produce toxin B only.

Reference ranges

Standard reference

Negative (not detected) # REVIEWER FLAG: Confirm Access Medical Laboratories result reporting format — some platforms report Toxin A and Toxin B as discrete positive/negative results; others report a combined Toxin A&B result as a single positive/negative output. Confirm whether Access Medical Laboratories distinguishes toxin A from toxin B individually or reports them as a combined result.

Functional medicine optimal

Not applicable — qualitative negative/positive assay. Negative (not detected) is the expected result in all healthy and asymptomatically colonised individuals being appropriately tested.

Units

Qualitative (Positive / Negative)

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.