Faecal elastase-1: lyophilization of stool samples prevents false low results in diarrhoea

Scand J Gastroenterol. 2001 Jul;36(7):771-4. doi: 10.1080/003655201300192058.

Abstract

Background: In patients with diarrhoea, faecal elastase-1 is used to detect exocrine pancreatic insufficiency. Diarrhoea is defined as >85% stool water content.

Methods: We analysed elastase-1 in 519 stool samples from 310 patients unprocessed as well as after lyophilization in a standard laboratory lyophilizator. Stool water content was calculated by weight difference before and after lyophilization.

Results: 151 stool samples were classified as 'diarrhoea' (mean stool water content 88.8%); all others had a mean water content of 75.4%. In the 'diarrhoea' samples, elastase-1 levels were considerably higher after lyophilization--with a calculated normal water content of 75% (606 +/- 359 microg/g, mean +/- s)--compared to measurement when unprocessed (279 +/- 151 microg/g; P < 0.0001). In 16 of the 151 cases (11%), the abnormally low elastase-1 level below 200 microg/g found in unprocessed stools proved normal (>200 microg/g) after lyophilization and correction for stool water content.

Conclusion: Diarrhoea can result in falsely decreased elastase-1 levels in a number of patients with non-pancreatogenic diarrhoea. Lyophilization is a simple measure by which to determine elastase-1 independently of stool water content. Lyophilization of stool samples can therefore help to prevent wrong positive elastase-1 test results.

Publication types

  • Research Support, Non-U.S. Gov't
  • Validation Study

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Case-Control Studies
  • Child
  • Child, Preschool
  • Diarrhea / etiology*
  • Exocrine Pancreatic Insufficiency / complications*
  • Exocrine Pancreatic Insufficiency / diagnosis*
  • Exocrine Pancreatic Insufficiency / enzymology
  • False Positive Reactions
  • Feces / chemistry*
  • Feces / enzymology*
  • Female
  • Freeze Drying / methods*
  • Freeze Drying / standards*
  • Humans
  • Infant
  • Male
  • Middle Aged
  • Pancreatic Elastase / analysis*
  • Pancreatic Function Tests / methods*
  • Pancreatic Function Tests / standards*
  • Sensitivity and Specificity
  • Water / analysis

Substances

  • Water
  • Pancreatic Elastase