Determination of fecal fat concentration by near infrared spectrometry for the screening of pancreatic steatorrhea.

Abstract

Near infrared reflectance analysis (NIRA) is a useful test for diagnosing fat malabsorption. Three-day stool collection and determination of fecal fat output are recommended. The measurement of fat concentration on spot samples may be of some use only in screening malabsorption of pancreatic origin; moreover, it does not discriminate between steatorrhea resulting from pancreatic insufficiency and that caused by gastrointestinal disorders. NIRA has been proposed as an accurate method for the determination of fecal fat excretion. The aim of this study was to ascertain whether utilization of this technique to measure fat concentration in spot samples of feces is useful in screening for malabsorption. Twenty-five patients with chronic pancreatic disease and 95 with other digestive disorders were studied. In all patients, fecal fat assay with NIRA was performed on three different samples from each daily stool collection for 3 d. In 14 patients with pancreatic disease and 21 with gastrointestinal disorders, a colorimetric assay for fecal fat was performed for comparison. When mean 3-d or daily fat fecal output were considered, a strict linear relationship was found between NIRA and the colorimetric method (r = 0.97 and 0.94, respectively). Using fat concentration, the two tests correlated less well (r= 0.74). Fat concentration was significantly higher in pancreatic than in nonpancreatic steatorrhea, even though values overlapped widely, and thus discrimination was not possible. The diagnostic efficiency of fat concentration for pancreatic and nonpancreatic steatorrhea was 72 and 61%, respectively.