What Is Secretin?
Your small intestine produces a hormone called secretin when partially digested food from the stomach arrives in the small intestine. Secretin makes the pancreas release a fluid that contains inactive digestive enzymes and bicarbonates. This fluid moves from the pancreas into the upper portion of the small intestine (the duodenum). The fluids neutralize stomach acids to activate pancreatic enzymes. These enzymes help break the food down and absorb its nutrients. (LTO 2, MH)
Some pancreas diseases make it more difficult for the small intestine to produce secretin. When this happens, the pancreas cannot deliver enough digestive enzymes to the small intestine to help in the digestion process. This is called pancreatic insufficiency.
Cystic fibrosis (CF), pancreatitis (inflammation of the pancreas), and pancreatic cancer may cause pancreatic insufficiency. (MP)
CF is a genetic disease. If you have CF, you may develop mucus in your lungs and pancreas. Mucus can make the delivery of pancreatic fluid to the duodenum difficult. Children who have pancreatic insufficiency often have CF. They may also be malnourished. (LTO 1, LTO 2)
If you have chronic pancreatitis or pancreatic cancer, you may have tissue damage to the cells that produce enzymes. You may also have damage to the duct that delivers enzymes to the small intestine. If you have this damage, you may not have enough pancreatic enzymes to properly digest food in the duodenum. In adults, this condition is most commonly associated with pancreatitis. However, damage can also be caused by pancreatic cancer, which is less common. (LTO 2)
A doctor will need to perform several tests to diagnose pancreatic diseases. One test shows how well the pancreas functions in response to secretin. This test is invasive and is conducted only when other evidence indicates pancreatic insufficiency. (Mayo)
The secretin stimulation test evaluates how well the pancreas functions during digestion. It is also called the pancreatic function test. (MH, MP)
The Test Procedure
A doctor tests how the pancreas responds to secretin by inserting a tube through your nose into your esophagus and through your stomach until the tube reaches the duodenum. You may experience irritation in your nose and a gagging sensation when the tube is inserted. The doctor puts secretin into the body intravenously. If pancreatic fluid is released in response to the secretin, it will be removed through the tube within an hour or two. (MH, MP)
There is a small risk that the tube could be inserted into your trachea and go into your lungs instead of the esophagus, but your doctor will be sure the tube is placed correctly before continuing with the test. (MH, MP)
Preparing for the Test
You will need to fast for 12 hours before the test and not eat any food or drink any liquids, including water.
If your test results are abnormal, this means you have some degree of pancreatic insufficiency. (MH, MP) Abnormal results may mean you have cystic fibrosis, pancreatitis, or pancreatic cancer, but abnormal results are not enough for a doctor to diagnose these diseases without performing other tests. (Mayo, MH, MP)
It is not easy to diagnose pancreatitis or pancreatic cancer. According to the Mayo Clinic, there are different types of pancreatitis. It may be acute or chronic, and each type requires different tests before a doctor can make a diagnosis. (Mayo) If you have pancreatitis enzymes that are normally inactive until they reach the small intestine become activated and start digesting while they are still in the pancreas. Symptoms of pancreatitis include abdominal pain, nausea, and vomiting. These symptoms are not specific to diseases of the pancreas and can point to a number of diseases. (LTO 2)
If your doctor tests you for pancreatitis, your testing will usually begin with blood work. According to the Mayo Clinic, you will also undergo stool testing and other radiology tests. (Mayo)
Many symptoms of pancreatic cancer are similar to those of pancreatitis. If you have chronic pancreatitis, you have a higher-than-normal risk of contracting pancreatic cancer. If your doctor believes you might have pancreatic cancer, he or she will order other tests, including a biopsy of the pancreas. (Mayo)