Guanidinoacetate and Creatinine, Urine — Calculated Ratio
A urine test that measures guanidinoacetate relative to creatinine, helping evaluate creatine metabolism and possible creatine disorders.
["This ratio can help identify abnormalities in creatine metabolism when interpreted alongside symptoms and other tests."]
Key facts at a glance
- LOINC
- 34155-2
- Short code
- Guanidinoacetate/Creat Ur-sRto
- Synonyms
- Guanidinoacetate/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 guanidinoacetate, a compound involved in creatine production, in urine and compares its amount with urinary creatinine. The calculated ratio helps account for variation in urine concentration.
Why might I need this test?
It may be used when symptoms suggest a disorder of creatine metabolism, such as unexplained developmental delay, muscle weakness, low muscle tone, or seizures. It is usually interpreted with other laboratory and genetic tests.
How is the test performed?
A urine sample is analyzed for guanidinoacetate and creatinine using laboratory testing methods. The laboratory calculates the guanidinoacetate-to-creatinine ratio from the measured values.
How do I prepare for the test?
Follow the laboratory's instructions for urine collection, including whether a first-morning or timed sample is required. Tell your clinician if you are pregnant, taking medications, or have a known kidney or urinary tract condition.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
An elevated ratio may occur with reduced activity of enzymes needed to synthesize creatine or guanidinoacetate. It can be associated with muscle weakness, low muscle tone, developmental problems, seizures, or movement difficulties, particularly in children. Urinary creatinine, kidney function, age, and medication use can affect interpretation, so an abnormal result requires clinical correlation.
Short name
Urinary Guanidinoacetate/Creatinine Ratio
Frequently asked questions
What does the urine guanidinoacetate/creatinine ratio measure?
What conditions can cause an elevated result?
Does this test alone diagnose a creatine disorder?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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