FAT - faeces

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Specimen: Minimum of 72 hour faecal collection (comprising at least 150 g of faeces). Patient must be on a diet containing 70-100 g of fat per day for at least four days prior to, and during, the test.

Method: Gravimetric or titrimetric. If the patient is taking medium chain triglycerides this must be stated on the request form, as a special analytical procedure is required. Faecal fat content can be assessed qualitatively by microscopy.

Reference Interval: Total lipid <20 mmol/24 hours.

Application: Investigation of malabsorption syndrome and documentation of steatorrhoea.

Interpretation. High levels are seen in steatorrhoea caused by pancreatic, biliary or intestinal disorders. Inadequate specimen collection can result in failure to detect steatorrhoea.

Reference: Jeejeebhoy KN et al. Clin Biochem 1970; 3: 157-163.

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