Sepiapterin/Creatinine Ratio, Urine
Measures urinary sepiapterin relative to creatinine, helping evaluate sepiapterin metabolism and other urinary metabolites.
["This urine test helps assess sepiapterin metabolism while accounting for differences in urine concentration."]
Key facts at a glance
- LOINC
- 75044-8
- Short code
- Sepiapterin/Creat Ur-sRto
- Synonyms
- Sepiapterin/Creat Ur-sRto
- Category
- kidney
- Sample
- urine
- Container
- Sterile urine container
- Units
- N/A
- Ref low
- 0.8
- Ref high
- 1.2
- Critical range
- — – 5 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 85610
- SNOMED
- 396252006
- 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 the amount of sepiapterin in urine relative to the amount of creatinine. Sepiapterin is involved in making tetrahydrobiopterin, a substance needed for proper neurotransmitter function.
Why might I need this test?
This test may be ordered as part of an evaluation for suspected neurotransmitter or metabolic conditions. It is often interpreted with other urine metabolites, genetic testing, and clinical findings.
How is the test performed?
A urine sample is tested for sepiapterin and creatinine. The laboratory divides the sepiapterin result by the creatinine result, which helps account for variations in how concentrated the urine is.
How do I prepare for the test?
Follow your healthcare provider's urine collection instructions, including whether a timed collection is required. Maintain normal fluid intake unless instructed otherwise, and tell the provider about medications and supplements that may affect the results.
Reference range
INR: 0.8-1.2 (warfarin: 2.0-3.0)N/A
Inform your healthcare provider if you are taking blood thinners. No special preparation required.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
An abnormal ratio may indicate altered sepiapterin metabolism, including conditions that affect tetrahydrobiopterin production. Changes in urine creatinine, kidney function, hydration, medications, or supplements can also affect the result, so it should be interpreted by a qualified clinician alongside other tests.
Short name
Urinary sepiapterin/creatinine ratio
Frequently asked questions
Is this the same as a routine urine creatinine test?
Why is creatinine included in the result?
Does an abnormal result confirm a genetic 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