Urine Phosphoserine/Creatinine Ratio
This urine test measures phosphoserine relative to creatinine, helping evaluate phosphoserine excretion while accounting for urine concentration.
["An elevated result may indicate increased phosphoserine excretion, but it must be interpreted with symptoms and other laboratory findings."]
Key facts at a glance
- LOINC
- 28600-5
- Short code
- Phosphoserine/Creat Ur-Rto
- Synonyms
- Phosphoserine/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?
Phosphoserine is a non-protein building block involved in serine metabolism. This test compares the amount of phosphoserine in urine with the amount of creatinine, which helps account for differences in urine concentration.
Why might I need this test?
The test may be used to investigate unusual phosphoserine levels or symptoms suggesting an inherited disorder of amino acid metabolism. It can also help assess phosphoserine excretion when evaluating suspected serine metabolism disorders.
How is the test performed?
A urine sample is collected and analyzed in the laboratory for phosphoserine and creatinine. The laboratory then calculates the phosphoserine-to-creatinine ratio. The type of urine collection will depend on your healthcare provider's instructions.
How do I prepare for the test?
Follow the urine collection instructions provided by your healthcare professional. Your clinician may advise you about supplements, medications, or diet changes before the test. If a timed collection is requested, record the collection period and urine volume as directed.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
A higher-than-expected ratio may reflect increased phosphoserine excretion, reduced kidney handling, or an inherited disturbance in serine metabolism. Interpretation depends on urine collection, kidney function, diet or supplements, symptoms, and other laboratory results. A single result does not by itself establish a diagnosis.
Short name
Urine phosphoserine/creatinine ratio
Frequently asked questions
What does the phosphoserine/creatinine ratio measure?
Is this the same as a serum phosphoserine test?
What if my result is abnormal?
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