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Octadecanoic Acid (Octadecanoate)/Creatinine Ratio, Stool

Published: August 9, 2026Updated: August 16, 2026

This stool test compares the amount of octadecanoate, a fatty acid, with creatinine in the same sample. It may help evaluate fat handling and intestinal absorption.

Quick summary

["The ratio may help identify excess fatty material in the stool and assess possible problems with digestion or nutrient absorption."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
47779-4
Short code
Octadecanoate/Creat Ur-sRto
Synonyms
Octadecanoate/Creat Ur-sRto
Category
kidney
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What is this test?

This test measures octadecanoic acid, also called octadecanoate, and creatinine in a stool sample. The laboratory compares their amounts to produce a ratio that accounts for differences in the quantity of stool collected.

Why might I need this test?

A clinician may order this test when symptoms suggest difficulty digesting or absorbing dietary fat. It can also be used alongside other stool, blood, and clinical findings to investigate chronic diarrhea or other digestive complaints.

How is the test performed?

A stool sample is collected in the container provided by the laboratory. The sample is analyzed for octadecanoate and creatinine, and the results are used to calculate the octadecanoate-to-creatinine ratio.

How do I prepare for the test?

Follow the laboratory's collection instructions, including any requested collection time and storage conditions. Do not add cleaner, water, or other materials to the container unless your clinician specifically instructs you to do so.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Stool Octadecanoate/Creatinine Ratio

Frequently asked questions

What does an elevated octadecanoate/creatinine ratio mean?
It may suggest increased amounts of this fatty acid in the stool relative to the amount of sample. Possible explanations include poor fat digestion, reduced intestinal absorption, or diet-related factors.
Is this the same as a routine fecal fat test?
No. It measures a specific fatty acid relative to creatinine rather than directly measuring all fecal fat. A clinician may interpret it as part of a broader digestive evaluation.
How is a stool sample collected for this test?
Usually, a portion of stool is placed in a labeled, laboratory-provided container. Follow the instructions for timing, refrigeration, and transport to keep the sample suitable for analysis.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy