Butterfat absorption--a valuable screening test in malabsorption.

The diagnosis of intestinal malabsorption is difficult to make without the use of specific tests such as endoscopic retrograde cholangiopancreatography (ERCP) or duodenal biopsy which are invasive and potentially hazardous. Faecal fat estimation or C14 Triolein breath tests have limitations as screening tools are time consuming and expensive. The butterfat absorption test (BFAT) is, in contrast, a simple, quick and cheap test for fat malabsorption. We have assessed the performance of this test in a blinded retrospective study of all such procedures performed in a teaching hospital over an 8 year period. One hundred and fourteen cases of suspected malabsorption had one or more butterfat tests. These were divided into absorbers and malabsorbers without knowledge of the butterfat test results. We found the butterfat test to have a sensitivity of 88% and a specificity of 94% using a cut-off of 20 light-scattering intensity units to discriminate normal from abnormal tests. At this level, predictive values are 91% for a positive result and 92% for a negative. These results are similar to those reported with the C14 Triolein breath test and adjusted faecal fats. We conclude that the butterfat test is a simple, cheap and effective screening test in the diagnosis of malabsorption.