From the Guidelines
Elevated intestinal isoenzyme is a significant indicator of intestinal damage or increased permeability, necessitating a comprehensive gastrointestinal workup to identify underlying conditions such as inflammatory bowel disease, celiac disease, or bacterial overgrowth. The clinical significance of an elevated intestinal isoenzyme, particularly alkaline phosphatase, lies in its association with various gastrointestinal disorders. According to the American Gastroenterological Association's medical position statement on the evaluation of liver chemistry tests 1, the presence of abnormal serum liver chemistries, including alkaline phosphatase elevations, warrants a diagnostic evaluation to determine the underlying cause. Key considerations in the evaluation of elevated intestinal isoenzyme include:
- Determining the presence of conjugated or unconjugated hyperbilirubinemia to guide further diagnostic testing
- Assessing for symptoms and signs of liver disease, such as jaundice, pruritus, or abdominal pain
- Evaluating for common hepatic conditions, including viral hepatitis, autoimmune hepatitis, or cholestatic disorders
- Considering the use of imaging studies, such as ultrasonography, computerized tomography, or magnetic resonance imaging, to evaluate the liver and biliary tract
- Ordering serologic tests, including HAV-IgM, HBsAg, and Hepatitis B core antibody-IgM fraction (HBcIgM), HCV antibody, and considering HCV-RNA 1 Treatment of elevated intestinal isoenzyme focuses on addressing the underlying condition, rather than the enzyme elevation itself. For example, inflammatory bowel disease may require anti-inflammatory medications, while celiac disease necessitates strict gluten elimination. Bacterial overgrowth typically responds to antibiotics, highlighting the importance of a targeted therapeutic approach based on the underlying diagnosis.
From the Research
Significance of Elevated Intestinal Isoenzyme
- Elevated intestinal isoenzyme, specifically intestinal alkaline phosphatase, has been observed in patients with liver disease, particularly those with cirrhosis due to hepatocellular diseases 2.
- The clinical utility of serum determinations of alkaline phosphatase isozymes was evaluated in patients with diseases of the gastrointestinal tract and the liver, and it was found that intestinal alkaline phosphatase is a significant contributor to the total alkaline phosphatase activity in patients with liver disease 2.
- There is no direct evidence linking elevated intestinal isoenzyme to inflammatory bowel disease (IBD) or celiac disease, although studies have found an increased risk of celiac disease in patients with IBD and vice versa 3, 4.
- Markers of intestinal inflammation, such as lactoferrin, fecal leukocyte analysis, and calprotectin, have been studied for the diagnosis of infectious gastroenteritis, but their sensitivity and specificity as stand-alone tests are limited 5.
- The role of endoscopy in the diagnosis, management, and treatment of IBD has been established, but its relationship to elevated intestinal isoenzyme is not clear 6.