Doctors diagnose EPI using a range of stool tests, blood tests, and sometimes scans. But a diagnosis may be challenging.
No single test can do it, and doctors often use the results of multiple tests as part of an overall clinical picture that includes symptoms and signs of malabsorption and malnutrition.
Testing is just one part of the EPI puzzle that your healthcare team will have to solve, but it still provides essential information.
Stool Tests
A stool, or fecal elastase-1 (FE-1), test is often the first performed for EPI given the hallmark symptom of steatorrhea.
The healthcare provider gives you a container for a stool sample, and you’ll need to provide a semisolid or solid stool.
This tests levels of the pancreatic enzyme elastase, which supports protein digestion, in the intestines.
This enzyme survives passing through the digestive system, so it shows up in stools.
Low levels in the stool suggests you may have EPI.
FE-1 testing is accurate at showing severely impaired pancreas function, such as for children with cystic fibrosis.
But while FE-1 isn’t as expensive or invasive as other tests, it often gives false-positive or false-negative results.
For example, it’s also unsuitable for use when a person has particularly watery stools, because the FE-1 content may be diluted, potentially giving a false-positive result. An FE-1 test also isn’t effective at detecting mild EPI. A doctor may elect to start PERT without this type of test, especially if a person has underlying pancreas issues and symptoms like steatorrhea.
Measuring the fat content of stools through a fecal fat test may show how much fat the body is unable to digest. But doctors rarely recommend this test during routine screening for EPI, because a person needs to eat a specific, moderate-fat diet containing definite fat content for five days beforehand. This places a high burden on the patient.
Fecal fat testing plays a role in clinical research more than in practical medicine. But doctors might suggest a fecal fat test if a person isn’t showing a good response to PERT.
Blood Tests
Healthcare professionals may collect a blood sample to check levels of the fat-soluble nutrients A, D, E, and K and other minerals. People with EPI have difficulty processing fats, so these levels may be lower for them. These tests may help doctors identify malnutrition.
Blood tests can also measure trypsinogen, the pancreatic enzyme that converts to trypsin. This can be a helpful way for doctors to check how you’re responding to PERT treatment, as FE-1 levels don’t change when you take pancreatic enzymes from outside the body, but trypsin levels do.
Pancreatic Function Tests
An endoscopic pancreatic function test (ePFT), also known as a secretin pancreatic function test, is the most accurate way to directly test how the pancreas is working.
A gastroenterologist inserts a flexible telescope into a person’s mouth while they’re under anesthesia and passes it down through the digestive system; this process is known as an endoscopy. The gastroenterologist administers a hormone called secretin that usually triggers the release of digestive enzymes, then collects pancreatic juice every 15 minutes for an hour to measure the concentration of a compound called bicarbonate. A pancreas will make enough bicarbonate if it is working well.
Despite its accuracy, ePFT is infrequently done and usually limited to specialized centers because it’s complex and time-consuming. The American Gastroenterological Association says that direct pancreatic function tests (ePFTs included) are promising but not widely available in the United States.
The American Pancreatic Association further states that these tests are great at diagnosing early chronic pancreatitis but are often saved for patients being evaluated for chronic abdominal pain and suspected chronic pancreatitis.
Imaging Tests
These can’t directly diagnose EPI, but doctors will often carry out a range of imaging tests to rule out or identify underlying pancreatic problems, such as pancreatic cancer, advanced pancreatitis, or a shrinking pancreas.
These may include a computed tomography (CT), magnetic resonance imaging (MRI) scan, or endoscopic ultrasound (EUS).
During an EUS, along with capturing imaging of the pancreas, the gastroenterologist may also collect a biopsy using a fine needle attached to the end of the scope if they find any tumors or cysts.