Trypsin and chymotrypsin in duodenal aspirate and faeces in response to secretin and cholecystokinin-pancreozymin

Abstract

SUMMARYThe secretion of trypsin and chymotrypsin into the duodenum in response to secretin and CCK-PZ has been compared with the faecal excretion of the enzymes following similar stimulation in 47 individuals undergoing clinical investigation. The faecal output of chymotrypsin correlated well, but trypsin less satisfactorily, with the secretion of the respective enzymes into the duodenum. The faecal excretion of chymotrypsin following stimulation with secretin and CCK-PZ can therefore be used as an index of pancreatic enzyme-secretory capacity.The secretion of bicarbonate into the duodenum in response to secretin is a satisfactory and widely used criterion for assessing the secretory capacity of the exocrine pancreas (Wormsley, 1972a) despite the assumed origin of the bicarbonate from the biliary system and duodenal mucosa as well as the pancreas.Recently, the availability of cholecystokinin-pancreozymin (CCK-PZ) and derivatives or analogues has resulted in attempts to utilize the specific pancreatic secretion of enzymes into the duodenum to measure pancreatic exocrine function (Burton, Evans, Harper,

A UK Survey of Laboratory-Based Gastrointestinal Investigations

“…Faecal chymotrypsin is used by most laboratories in preference to faecal trypsin and is a better indicator of pancreatic dysfunction since the latter is susceptible to digestion during its transit through the gut. 18 The survey showed wide variations in reference ranges between laboratories. With the problems of establishing locally derived reference ranges for GI tests, the practice of transcribing them from publications is understandable.…”

Tests of Exocrine Pancreatic Function

“…Further inactivation may also be caused by colonic inhibitors (Goldberg, 1974) and by excessive growth of intestinal flora; in normal stools chymotrypsin is stable for up to four days. Such intestinal losses may be diminished with concomitant improvement in discrimination if purgatives are used during a timed collection period (Sale et al, 1974). In this way more than half the secreted chymotrypsin can be recovered in the faeces.…”

“…There is a correlation between faecal chymotrypsin output and the amounts of bicarbonate and enzymes secreted into the duodenum following stimulation (Ammann, 1969;Sale et al, 1974). Thus faecal enzyme determinations can aid the selection of cases for this more detailed examination and are useful for following progressive pancreatic disorders.…”

“…However, low results occur in some cases of steatorrhoea without other evidence of impaired pancreatic function and have been attributed to increased buffering action of faecal components or to overgrowth of intestinal flora. Avoidance of such effects is likely if purgation is used (Sale et al, 1974).…”

Limitations of faecal elastase-1 and chymotrypsin as tests of exocrine pancreatic disease in adults

“…Faecal chymotrypsin (FCT) is most frequently used, but some activity is lost during transit through the intestine before excretion in the faeces. 1 Faecal immune reactive elastase -1 (FEL) has the potential advantage of being stable during gut transit and is una¡ected by enzyme replacement therapy.…”