Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (776 page)

   Does not differentiate among inflammatory bowel pathologies.

   False negatives are more common in children and teenagers than in adults.

   Fecal calprotectin levels increase after use of nonsteroidal anti-inflammatory drugs, that levels may change with age.

   Bleeding (e.g., nasal or menstrual) may cause an elevated fecal calprotectin level.

CANCER ANTIGEN 15-3 (CA 15-3)

   Definition

   This glycoprotein is a mucinous carbohydrate antigen product of the MUC1 gene expressed on various adenocarcinomas, especially breast. It is a high molecular weight (300–450 kDa) 1 polymorphic epithelial mucin.

   
Normal value:
<38 U/mL.

   Use

   Marker for breast carcinoma. United States Food and Drug Administration (USFDA) approval is only for detection of breast carcinoma recurrence before symptoms and to monitor response to treatment. Significant change is ±25%.

   Not approved for screening, although increased values may occur ≤9 months before clinical evidence of disease.

   Interpretation

Increased In

   Approximately 80% metastatic breast cancer

   Pancreas, lung, ovarian, colorectal, and liver cancers with less specificity