A positive Saccharomyces cerevisiae IgA (ASCA IgA) indicates the immune system has made mucosal antibodies against Saccharomyces cerevisiae. It’s more commonly associated with Crohn’s disease than ulcerative colitis and can support — but does not confirm — a diagnosis of inflammatory bowel disease. Results must be interpreted with symptoms, endoscopy, imaging and inflammatory markers; discuss further evaluation with a gastroenterologist.

Anti‑Saccharomyces cerevisiae antibodies (ASCA) are immune proteins that target cell‑wall components of baker’s yeast. They act as serologic markers often present in Crohn’s disease, helping distinguish it from ulcerative colitis and indicating higher risk of complicated, fistulizing, or stricturing disease. ASCA support clinical assessment but are neither definitive diagnostic tests nor proof of causation.

Anti‑Saccharomyces cerevisiae antibodies (ASCA), particularly ASCA IgA and IgG, are commonly positive in Crohn’s disease and can help distinguish it from ulcerative colitis (where p‑ANCA is more typical). ASCA is supportive but not diagnostic alone; it’s used with clinical evaluation, endoscopy, imaging, and other tests since sensitivity is modest.

Anti‑Saccharomyces cerevisiae antibodies (ASCA) are most commonly positive in Crohn’s disease, particularly small‑bowel disease. They may be positive less often in ulcerative colitis and other inflammatory bowel conditions, and rarely in some infections or healthy people. ASCA supports but does not confirm diagnosis; results are interpreted alongside clinical, endoscopic and imaging findings.

A positive IgA result means IgA antibodies are present or total IgA is elevated. This can reflect a recent or ongoing mucosal immune response from infections, autoimmune disease, liver disease, allergies, or specific conditions (for example, a positive anti‑tTG IgA suggests possible celiac disease). Your clinician will correlate symptoms, order confirmatory or alternate tests, and consider IgA deficiency which can affect accuracy.

Saccharomyces cerevisiae is usually harmless but can cause opportunistic infections, especially in immunocompromised or critically ill people. Reported diseases include fungemia/sepsis, invasive bloodstream infections, endocarditis, urinary tract and wound infections, peritonitis, and pneumonia. Probiotic strains (e.g., S. boulardii) have been linked to breakthrough fungemia and localized infections in patients with central lines, severe illness, or impaired immunity.