Case Presentation: A 50-year-old gentleman was admitted to the hospital medicine service for workup and evaluation of 3 days of epigastric abdominal pain. His history was significant for two recent admissions for episodes of acute pancreatitis within the preceding 2 months and alcohol use disorder (4 weeks sober) without cirrhosis. Physical exam was remarkable for moderate ascites and epigastric abdominal tenderness. In addition, computed tomography (CT) imaging showed a large right-sided pleural effusion along with ascites, increased stranding around the tail of the pancreas, and a fluid collection in the upper abdomen thought to represent pancreatic pseudocyst. Serum amylase the day of admission was 103 U/L (normal 26-102 U/L) and serum lipase was elevated at 243 U/L (normal 12-61 U/L). Paracentesis performed the day of admission demonstrated mildly elevated peritoneal fluid amylase (223 U/L), and a high level of lipase 1000 U/L, SAAG of 0.7 g/dL, and total protein 3.6 g/dL. On day 2, pleural fluid analysis showed amylase 877 U/L and lipase 5620 U/L. Based on the substantially elevated lipase levels in ascitic and pleural fluid, pancreatic duct leak was highly suspected and confirmed by magnetic resonance cholangiopancreatography (MRCP). Six days after admission, endoscopic ultrasound (EUS) revealed a peripancreatic area of walled-off necrosis which was drained by creation of cystogastrostomy with stenting. After the procedure, the patient’s pain improved and he was discharged home on an oral pain regimen.
Discussion: Typically in acute pancreatitis serum amylase is elevated to greater than three times the upper normal limit; however, in greater than 20% of patients with acute alcoholic pancreatitis serum amylase may not be significantly elevated.[1,2] When these patients present with complications such as ascites or pleural effusion, levels of amylase in ascitic or pleural fluid may not be a good diagnostic marker of pancreatic duct leakage causing ascites or pleural effusion. The clinical value of lipase measurement in ascitic or pleural fluid has not been well described and may be a helpful marker for diagnosis of pancreatic ascites or pancreatic pleural effusion when serum lipase is elevated but amylase is not significantly increased.
Conclusions: Although elevated amylase in fluid usually indicates pancreatic duct leak as a cause of ascites or pleural effusion, in patients who have pancreatitis without a significant rise in serum amylase, this may not be reliable. This case illustrates the utility and importance of lipase measurement in ascitic and pleural fluid to diagnose pancreatic duct leak as a cause for ascites and pleural effusion in the subset of patients who have pancreatitis without significant serum amylase elevation.