Very Long Chain Fatty Acid C26:0 and Creatinine — Urine and Stool

What is this test?

This test measures very long-chain fatty acid C26:0, a type of fatty acid that can accumulate when the body does not process certain fats normally. The test name also includes creatinine, which may be used to account for differences in urine or stool concentration.

Why might I need this test?

A clinician may order this specialized test when symptoms suggest an inherited condition that affects fatty-acid processing or peroxisome function. The results are usually interpreted together with other laboratory findings, medical history, and physical examination.

How is the test performed?

A laboratory analyzes urine and/or stool samples for C26:0 and creatinine using a validated testing method. Depending on the order, urine may be collected once or over 24 hours, while stool is collected in a clean container.

How do I prepare for the test?

Follow the collection instructions provided by the laboratory or your clinician, including whether both urine and stool are needed. For a 24-hour urine collection, record the start and finish times and keep the container refrigerated if instructed. Do not change your diet or medications unless your clinician advises you to do so.