CA-125 Elevation in Gastroenteritis and Infection
Yes, CA-125 can be significantly elevated in patients with gastroenteritis or infection, particularly when peritoneal inflammation is present, and should not be interpreted as evidence of malignancy in these clinical contexts. 1
Mechanism of CA-125 Elevation in Infection
CA-125 is a natural product of mesothelial cells lining serosal surfaces (peritoneum, pleura, pericardium), not primarily a cancer-derived marker. 2 The key mechanisms include:
Peritoneal inflammation/infection directly stimulates mesothelial cells to produce CA-125, causing falsely elevated serum levels that can mimic malignancy. 1
Any condition causing mesothelial cells to be under pressure or inflammatory stress will elevate CA-125, including infections affecting serosal surfaces. 1, 2
Serosal fluid accumulation from any cause (including infectious processes) universally elevates CA-125 because mesothelial cells under pressure from fluid produce the antigen. 1
Specific Infectious Conditions Causing CA-125 Elevation
Peritoneal infections are among the most common causes of elevated CA-125 outside of malignancy, with levels frequently elevated in patients with peritoneal inflammation. 3, 4
Sepsis with abdominal involvement shows particularly high CA-125 levels, with abdominal sources of infection demonstrating mean levels of 62±55.5 U/mL. 5
Inflammatory bowel diseases (ulcerative colitis and Crohn's disease) show significantly elevated CA-125 levels compared to healthy controls, with levels of 17.29±24.50 U/mL in ulcerative colitis patients. 6
Tuberculous peritonitis can cause markedly elevated CA-125 levels, leading to unnecessary laparotomies when ovarian cancer is incorrectly suspected. 4
Clinical Interpretation Guidelines
Critical caveat: The presence of peritoneal inflammation, infection, or any serosal fluid accumulation requires cautious interpretation of CA-125 levels, as these conditions can produce elevations indistinguishable from malignancy. 1, 4
CA-125 testing should NOT be performed in patients with ascites of any cause, as it is universally elevated and nonspecific in this setting, according to the American Association for the Study of Liver Diseases. 1, 7
Serum CA-125 levels can be falsely increased in patients with peritoneal inflammation/infection and may not indicate malignancy even when significantly elevated. 1
In septic patients, CA-125 levels remain elevated throughout the acute illness, with persistently elevated levels (>35 U/mL) associated with disease severity rather than cancer. 5
Distinguishing Infection from Malignancy
When CA-125 is elevated and infection is suspected:
Clinical context is paramount: The presence of fever, acute inflammatory markers (elevated WBC, CRP), and acute symptom onset favor infection over malignancy. 3, 4
Imaging findings are more reliable than CA-125 alone: Look for evidence of inflammatory changes, fluid collections, or bowel wall thickening rather than solid masses or peritoneal nodularity. 7, 4
Serial measurements during treatment: CA-125 levels should decrease rapidly with successful treatment of infection, whereas malignancy-related elevations persist or progress. 5
CA-125 levels >1,000 U/mL were always associated with cancer in one study, but lower levels must be interpreted according to clinical context and the presence of infection or effusion. 3
Common Pitfalls to Avoid
Do not order CA-125 testing in patients with known or suspected peritoneal infection, as it provides no diagnostic value and may lead to unnecessary invasive procedures. 1, 7
Avoid using CA-125 as a single diagnostic tool when serosal involvement (peritoneal, pleural, or pericardial fluid) is present, as unnecessary laparotomies have been performed revealing benign infectious etiologies. 4
Remember that CA-125 elevation in the setting of acute gastroenteritis with peritoneal signs reflects mesothelial irritation, not occult malignancy. 2, 3