Pancreatic Exocrine Insufficiency（PEI）

Normally，the amount of postprandial lipase secretion under normal physiologic circumstances can up to 9000-18,000 USP units/min（Trang et al.2014）.The main symptoms of PEI include steatorrhea，a poor coefficient of fat absorption（CFA），and deficiencies in fat-soluble vitamins and essential fatty acids（Aloulou et al.2015）.Traditionally it is believed that pancreas had a large exocrine reserve.As published by Dimagno et al.，steatorrhea may not appear until lipase output were deceased to about 10%of normal.However this perspective has been challenged as the perception can lead to disregard for PEI and resultant delay in benefiting CP patients with adequate enzyme therapy（Duggan et al.2016）.(https://www.daowen.com)

How to implement pancreatic enzyme therapy？The first step is to affirm the etiology of the steatorrhoea.Second，whether nonenteric or enteric coated enzyme needs to be applied.Third is the dosing.The starting dose of enzyme is from 25,000 to 40,000 IU taken with food（Smith et al.2016）.Last but not least，it is the responsibility of physicians to educate their patients about the appropriate way to take enzymes and to verify the effect of enzymes（Berry 2014）.One patient may need to take approximately 10,000 USP units of lipase containing enteric coated microbead capsules/tablets per meal and 3000 USP units with snacks（Trang et al.2014）.When symptoms do not improve with PERT，it has been suggested that there is a need to rule out other possible causes，including small intestinal bacterial overgrowth（SIBO）（Capurso et al.2016）.