Pancreatic elastase-1 in fecal dry matter in health and disease

Abstract

Background: In patients with diarrhea , fecal pancreatic elastase-I (E-!) us used to detect or rule out exocrine pancreatic insufficiency . We recently could demonstrate (Gastroenterology 1998.114. A45 7) that dilution ofE-1 does occur in diarrhea, leading to false low results. Methods: A total of 512 consecutive stool samples from clinical routine and 100 stool samples from healthy control persons (49 f. 51 m, mean age 35 yrs.) were analyzed unprocessed as well as after lyophilization in a standard laboratory IyophiIisator. E-I was determined with a commercially available test kit (ScheBo Tech. Germany). Water content was calculated by weighing the samples on precision scales before and after lyophilization. Results : 137/512 clinical stool samples had a stool water content >85%; these were regarded as diarrhea. In those, mean E-I concentration in unprocessed stools was 395 ± 152 /Lglg, but was 855 ± 408 /Lglg when measured after lyophili zation and mathematical correction to a stool water content of 75% (p= O.OOO I) . In 11/137 diarrhea sample s (8%), E-I concentrations were lower than normal «200 /Lglg) when measured unprocessed, but were normal when corrected for the elevated water content of stools. In healthy controls. E-I was 3877 ± 2203 /Lglg(range 642 9465 /Lg/g); stool water content was 69 ± 6%. Leaving off the three lowest results, a cut-off value of 800 /Lg/g fecal dry matter can be defined as the normal limit. Conclusion: More than 25% of stool samples sent in for E-I determination can be classified as diarrhea. False low E-I concentrations do occur due to elevated stool water conten. This mistake can be avoided by lyophilization of stool samples and mathematical correction. We established reference values for fecal dry matter to be used in diarrhea and in doubtful cases.