Routinely checking for EPI in patients with chronic diarrhea, using fecal elastase, is a useful and effective diagnostic approach with values 100–200 μg/g of stool reflecting mild to moderate pancreatic insufficiency and 100 μg/g of stool indicating severe EPI.
Routinely checking for EPI in patients with chronic diarrhea, using fecal elastase, is unreliable in the absence of testing a formed stool.
The currently available tests for EPI can be classified as direct or indirect measures of exocrine pancreatic function. Unfortunately, many of these tests (eg, serum trypsin levels and qualitative stool fat) have poor sensitivity/specificity and/or are available at only limited centers (eg, the 13C mixed triglyceride (13C-MTG) breath test).
The 72-hour fecal fat test has been considered the “gold standard” for diagnosis, but has significant limitations. It is time-consuming and not easily tolerated by the patient, due to bloating, abdominal discomfort, flatulence, and worsening steatorrhea. Additionally, it is prone to errors in stool collection and recording of fat intake, and diseases that affect mucosal fatty acid uptake (eg, Crohn’s disease) can cause abnormal values. The 72-hour test is useful for measuring the effectiveness of pancreatic exocrine replacement therapy (PERT) in EPI.
Diagnostic testing that utilizes fecal elastase has several advantages. It does not require a timed stool collection or special diet, has a high negative predictive value, and a high sensitivity in moderate to severe EPI when the formed stools are analyzed. Moreover, it is noninvasive and if the patient is being treated with PERTs, the medication does not have to be discontinued. However, diagnostic testing using fecal elastase has a lower sensitivity and specificity in mild to moderate EPI, potentially resulting in underestimation of EPI.
For the test to be accurate, formed stools must be analyzed, so it is not useful in patients with loose, watery stools.
PERT should be started at the lowest dose available and taken any time before a meal and at bedtime.
Titrate the dose of PERT to the presumptive degree of PERT and administer PERT with the first bite of a meal, and consider adding extra enzymes during or towards the end of the meal.
Dietary management and lifestyle changes are recommended but differ, based on the cause of EPI. In patients with chronic pancreatitis, a low-fat diet is recommended to minimize the pain of the disease and—in conjunction with PERT—to treat steatorrhea. However, in patients with cystic fibrosis, low fat diets are no longer recommended. Fat-soluble vitamins A, D, E, and K should be supplemented and taken with PERT. It is helpful to consult a dietitian to assess nutritional adequacy. Smoking and alcohol cessation are recommended.