Sulfocysteine-to-Creatinine Ratio, Urine
A urine test that measures sulfocysteine relative to creatinine, helping screen for inherited disorders of cystine metabolism such as cystinosis.
["An elevated ratio may suggest a disorder affecting how the body processes cystine, but results need clinical confirmation."]
Key facts at a glance
- LOINC
- 34168-5
- Short code
- Sulfocysteine/Creat Ur-Rto
- Synonyms
- Sulfocysteine/Creat Ur-Rto
- 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 urine test measures sulfocysteine, a compound formed when the amino acid cysteine is processed, relative to urine creatinine. Creatinine helps account for differences in how concentrated the urine sample is.
Why might I need this test?
The test may be used to help screen for cystinosis and other rare inherited conditions that affect how the body transports or breaks down cystine. It is often ordered as part of an evaluation for unusual urinary findings or symptoms affecting growth, kidneys, eyes, or other organs.
How is the test performed?
A urine sample is collected and analyzed in a laboratory. The laboratory reports the amount of sulfocysteine in relation to the amount of creatinine in the same sample.
How do I prepare for the test?
Follow the laboratory's urine-collection instructions and tell the clinician about any medicines, supplements, or vitamin supplements you take. Do not make major diet or medication changes solely for this test unless your healthcare professional advises you to do so.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
An elevated sulfocysteine-to-creatinine ratio may indicate increased urinary sulfocysteine, which can occur in cystinosis or other inherited disorders of cystine metabolism. This screening result does not establish a diagnosis by itself and may need to be interpreted alongside symptoms, other laboratory tests, and possibly genetic testing.
Short name
Urine sulfocysteine/creatinine ratio
Frequently asked questions
What does the sulfocysteine-to-creatinine ratio measure?
What conditions can cause an elevated result?
Does an abnormal result confirm cystinosis?
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