Both qualitative and quantitative tests are used to identify excessive fecal fat. The qualitative test involves staining a specimen of stool with a special dye, then examining it microscopically for evidence of malabsorption, such as undigested muscle fiber and various fats.
The quantitative test involves drying and weighing a 72 hour stool specimen, then using an extraction technique to separate the fats, which are subsequently evaporated and weighed. This measurement of the total output of fecal fat over 24 hours in a three-day specimen is the most reliable test for steatorrhea.
The patient should abstain from alcohol during this test and maintain a high-fat diet (100gm per day) for three days before the test, and during the collection period. You should be given details for preforming this test from the testing laboratory.
Acceptable values are generally found within the range of 5-7gm of fat per 24 hour period. More than this amount suggest a fat absorption problem.