Understand the differences between acute and chronic pancreatitis and the laboratory test results used to establish the diagnosis of each.
Learn the clinical, laboratory, and radiographic abnormalities in patients with cancer of the pancreas.
Learn the clinical and laboratory criteria for the diagnosis of diabetes mellitus, gestational diabetes mellitus, and hypoglycemia.
Identify the different islet cell tumors and learn their associated laboratory test results.
The pancreas is an endocrine/exocrine organ transversely oriented in the retroperitoneum with its “head” nestled in the duodenum and its “tail” approaching the spleen, measuring approximately 20 cm long by 2 to 3 cm in thickness. Eighty-five percent of the organ is exocrine in function, consisting of cells that secrete digestion-related enzymes (many in their inactive “pro” form) into the gastrointestinal tract (Table 17–1), whereas the endocrine portion consists of hormone-producing cell clusters (islets of Langerhans) histologically interspersed throughout the exocrine cellular component. There are four major cell types that produce their respective hormone, as listed in Table 17–2.
TABLE 17–1Exocrine Pancreas |Favorite Table|Download (.pdf) TABLE 17–1 Exocrine Pancreas
|Enzyme ||Function |
|Amylase ||Catalyzes breakdown of complex carbohydrates into individual glucose residues |
|Lipase ||Catalyzes hydrolysis of triglycerides into monoglyceride and free fatty acids |
|Trypsin (storage form—trypsinogen) ||Cleaves digested proteins (protease) at carboxyl groups on lysine and arginine amino acids |
|Chymotrypsin (storage form—chymotrypsinogen) ||Cleaves digested proteins (protease) at peptide bonds of tryptophan, leucine, tyrosine, and phenylalanine |
|Elastase ||Cleaves digested proteins (protease) at carboxyl groups on glycine, alanine, and valine |
TABLE 17–2Endocrine Pancreas |Favorite Table|Download (.pdf) TABLE 17–2 Endocrine Pancreas
|Cell Type ||Hormone ||Major Functions |
|Alpha ||Glucagon ||Increases blood glucose |
|Beta ||Insulin ||Decreases blood glucose |
|Delta ||Somatostatin ||Inhibits insulin and glucagon release |
|Gamma ||Pancreatic polypeptide ||Regulates pancreatic function |
Pancreatitis is the most common exocrine disorder and diabetes is the most common endocrine disorder. In terms of malignancy, exocrine tumors (95%) tend to be adenocarcinomas arising from pancreatic ductal epithelium with the much less common endocrine tumors arising from the islets of Langerhans characterized by their “progenitor” cell (insulinoma, gluconoma, etc.) type.
Acute pancreatitis is an acute inflammatory disorder of the pancreas clinically characterized by acute to chronic epigastric pain with nausea, vomiting and, if severe enough, fever, hypotension, and tachycardia. The top three causes of acute pancreatitis are biliary tract obstruction (40% to 70%), alcohol abuse (25% to 35%), and idiopathic causes (20%). Other less frequent etiologies include hypercalcemia, hypertriglyceridemia, infection, mechanical (post procedure), and medication related. The latter cause is usually due to toxic metabolites or hypersensitivity reactions (e.g., asparaginase, azathioprine, estrogens, furosemide, sulfonamides, tetracycline, and thiazides). Hereditary forms of acute pancreatitis have also been described due to mutations in the trypsinogen gene ...