This serum blood lab test is not a routine test. A doctor will make this test in case of chronic abdominal pains together with other tests to exclude an inflammation.
The normal range of the lipase is very much different depending on the laboratory (in Europe usually 0-190 U/l). An elevation of the lipase (together with clinical sign of abdominal pain) and other serum blood tests for inflammation (CRP) might be caused by a pancreatitis. Secondary affections of the pancreas by gall stones could also cause these alterations. Renal failure could also cause high lipase.
There a some single cases of serum lipase elevation caused by irritable bowl syndrome. The clinical presentation is different and usually the patient has no severe inflammation signs.
Amylase is another serum enzyme. In case of a pancreatitis the lab tests show elevated values. However there is a distinct salivary-type of this enzyme. Patients with bulimia nervosa can have elevated amylase without pancreatitis.