FECAL ELASTASE-1 IS SUPERIOR TO FECAL CHYMOTRYPSIN IN THE
ASSESSMENT OF EXOCRINE PANCREATIC FUNCTION IN CYSTIC FIBROSIS
Walkowiak J, Herzig K-H, Strzykala K, Przyslawski J, Krawczynski M
Institute of Pediatrics, Szpitalna 27/33, Poznan, Poland
Objective: For the evaluation of exocrine
pancreatic function in cystic fibrosis (CF), both direct and indirect tests
are used. In pediatric patients, indirect tests - due to their lower
invasiveness - are preferred. Fecal tests are non-invasive and have been shown
to have a high sensitivity and specificity. However, there are no
comparative studies on their use in CF. Therefore, the aim of the present
study was to compare the sensitivity and the specificity of fecal
elastase-1 (E1) test to fecal chymotrypsin (ChT) test in a large cohort of
CF patients and healthy subjects (HS).
Material and methods: 123 CF patients and 105
HS were evaluated. In all subjects, E1 concentration and ChT activity were
measured. In CF group, fecal fat excretion was also determined. The
sensitivity and specificity of the E1 test and ChT test were compared.
Results: With a cut-off level of 3 U/g, ChT specificity
in HS was similar to that of E1, but E1 sensitivity in CF patients was
significantly higher (90.2% vs. 81.3%; p<0.006). With a cut-off level of
6 U/g, ChT and E1 sensitivity in CF patients was identical, but E1
specificity in HS was again significantly higher (98.1% vs. 90.5%;
p<0.014). In all CF patients with severe steatorrhea (>15g/d), E1
concentrations were abnormal and ChT activity was lower than 3 U/g. In
contrary, in pancreatic sufficient patients and patients with mild
steatorrhea (<15g/d), E1 sensitivity was significantly higher compared
to ChT (69.2% vs. 41.0%; p<0.006).
Conclusion: Fecal elastase-1 test is superior to fecal
chymotrypsin estimation with no regard to cut-off level of the latter
enzyme.