What is involved in a fat absorption test in the workup of exocrine pancreatic insufficiency (EPI)?

Updated: Aug 12, 2021
  • Author: Samer Al-Kaade, MD; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
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A fat absorption test is usually the first one ordered because there are many disease processes that can result in fat malabsorption. For quantitative measurement of fat absorption, a 72-hour fecal fat collection is often performed and is considered the standard. Qualitative tests include the acid steatocrit test and Sudan III stain of stool, but these tests are less reliable.

Patients are instructed to consume a normal amount (80-100 g/day) of fat before and during the collection. On the basis of this level of intake, fecal fat excretion in healthy individuals should be less than 7 g/day.

The current standard for measuring fat malabsorption is the coefficient of fat absorption (CFA), [12] which is the percentage of absorbed fat in the diet. Normally, the CFA is approximately 90%. The various diseases that can give rise to EPI will produce different degrees of pancreatic insufficiency and, hence, different CFAs. For example, cystic fibrosis often results in a CFA lower than 40%, which typically increases to more than 80% with therapy.

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