Fecal Fat (72-hour quantitative)
The 72-hour quantitative fecal fat test measures how much fat ends up in your stool over three days. Normally most dietary fat is absorbed, so excess fat in stool points to a digestion or absorption problem.
Too much fat in the stool, called steatorrhea, can signal that fat isn't being digested or absorbed properly, as with pancreatic enzyme deficiency, bile problems, or conditions affecting the intestinal lining like celiac disease. It helps explain greasy, bulky, or foul-smelling stools and unexplained weight loss.
A high amount of fat in the stool suggests fat malabsorption, which can stem from pancreatic, liver or bile duct, or intestinal causes. An elevated result points toward further evaluation to find the underlying reason rather than naming one cause by itself.
A result within the normal range suggests fat is being digested and absorbed as expected, which is generally reassuring.
Labs typically define a normal upper limit for grams of fat excreted per day, and staying under it is the goal. Because the test depends on a controlled fat intake, your clinician should interpret the result with your diet and symptoms in mind.
Sources
Educational context only, not medical advice or a diagnosis. Reference ranges vary by lab, age and sex; always discuss your results with a clinician.