The human serum amylase, mainly from the pancreas and salivary glands, is also present in small amounts in other tissues. A certain amount of amylase is present in normal human serum, which is metabolized in the liver and later excreted through the kidneys. Acute pancreatitis and chronic pancreatitis can cause an increase in serum amylase. In addition, if liver cysts, ascites, or pancreatic tumors are present, serum amylase can also be increased. Other causes of increased serum amylase include perforation caused by peptic ulcer, intestinal obstruction, and mesenteric obstruction, and acute appendicitis can also cause increased serum amylase.