Acute severe pancreatitis blood amylase is not always elevated, but sometimes decreases instead. Here are the guidelines for the diagnosis and treatment of pancreatitis in China and the United States: Chinese guidelines for the diagnosis and treatment of acute pancreatitis: Clinically, acute, persistent abdominal pain (occasionally without abdominal pain), increased serum amylase activity > 3 times the upper limit of normal values, imaging suggesting pancreatic with or without morphological changes, excluding other diseases. There may or may not be other organ’ dysfunction. In a few cases, serum amylase activity is normal or mildly elevated. US Clinical Guidelines for Acute Pancreatitis: The diagnosis of acute pancreatitis generally requires 2 of the following 3 things: 1) Abdominal pain characteristic of acute pancreatitis; 2) Serum amylase and/or lipase ≥ 3 times the upper limit of normal: 3) CT manifestations characteristic of acute pancreatitis. This definition allows for the possibility of diagnosing acute pancreatitis with amylase and/or lipase < 3 times the upper limit of normal values. If the patient has abdominal pain characteristic of acute pancreatitis and the serum enzyme level is less than 3 times the upper limit of normal, a CT examination must be performed to confirm the diagnosis of acute pancreatitis. In addition, this definition also allows for the possibility that the patient has acute or chronic disease causing severe confusion that makes the abdominal pain unassessable.