@valerina30 The fecal elastase test is a “stool” test. It is ordered by a doctor and done by a lab. It’s purpose is to test your stool for pancreatic insufficiency. Depending on the number you get for pancreatic insufficiency, depends on how much Creon (or other brand enzyme) you need. After the test my doctor prescribed me 2-24,000 units of Creon per meal. However, my EPI number is in the moderate, not severe range. Those in severe range would have higher doses. Your weight also figures into the calculation.Either a GI doctor or dietician should be able to help you. Hope this helps.