Low serum pancreatic enzymes as measurement for pancreatic exocrine insufficiency in patients with chronic and autoimmune pancreatitis

Background & aims: Pancreatic exocrine insufficiency (PEI) and diabetes mellitus (DM) are frequent complications of chronic (CP) and autoimmune pancreatitis (AIP). Faecal elastase-1 (FE-1), the standard diagnostic test for PEI, only shows a low sensitivity for mild to moderate PEI, leaving early-stage PEI underdiagnosed. Earlier studies examining serum pancreatic enzymes as potential indicators for PEI showed varying results. We re-examined low pancreas-specific amylase (p-amylase) and lipase levels as screening method for PEI in CP and AIP, and secondary for DM and pancreatic atrophy. Material & Methods: In 242 patients (CP: n = 72, AIP: n = 50, controls: n = 120) we assessed the lowest levels of p-amylase and lipase within 6 and FE-1 within 12 months of radiologic imaging, and whether the patients had DM and pancreatic atrophy. Results: Significant group differences were found in the mean values of p-amylase, lipase and FE-1 (all p < 0.05), with lowest mean values in AIP patients. The prevalence of PEI was 73% in AIP vs. 47% in CP; DM was 38% vs. 25%. Concomitant PEI led to lower mean values of serum pancreatic enzymes, but the difference was not always significant. Overall, p-amylase and lipase showed a high specificity but moderate sensitivity in assessing PEI which improved with the degree of PEI. The prevalence of pancreatic atrophy was 72% in AIP and 71% in CP. Discussion: Normal serum pancreatic enzymes cannot exclude PEI, DM or pancreatic atrophy. However, reduced levels should prompt further investigation, especially in CP and AIP patients.