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Phosphoserine/Creatinine Ratio, Urine

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

Measures phosphoserine relative to creatinine in urine. The ratio helps account for urine concentration and may be used when evaluating disorders of amino acid metabolism.

Quick summary

["This urine test measures how much phosphoserine is present relative to creatinine, helping evaluate certain metabolic conditions."]

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

Key facts at a glance

LOINC
25128-0
Short code
Phosphoserine/Creat Ur-sRto
Synonyms
Phosphoserine/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 the amount of phosphoserine in urine relative to the amount of creatinine. Creatinine is used as a reference for urine concentration, so the ratio can help show whether phosphoserine excretion is unusually high.

Why might I need this test?

This test may be ordered as part of an evaluation of an inherited or metabolic disorder involving amino acids, particularly serine or phosphoserine metabolism. It may also be used to follow a previously identified abnormality.

How is the test performed?

A urine specimen is collected and analyzed in a laboratory. The laboratory measures phosphoserine and creatinine and then calculates their ratio.

How do I prepare for the test?

Follow the collection instructions provided by your healthcare professional, including whether a first-morning, timed, or random specimen is required. Record the collection time and tell the laboratory about relevant medications, supplements, supplements, or dietary changes.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Urine phosphoserine-to-creatinine ratio

Frequently asked questions

What does the urine phosphoserine-to-creatinine ratio show?
It compares the amount of phosphoserine in urine with the amount of creatinine. This helps account for differences in urine concentration.
Why is creatinine included in this test?
Creatinine is a common reference measurement for urine concentration. Using the ratio reduces the effect of variations in how concentrated a urine sample is.
Does an abnormal result confirm a metabolic disorder?
No. An abnormal result may prompt additional testing and clinical review, but it is not diagnostic by itself. Your healthcare professional will interpret it with your symptoms, history, and other laboratory findings.
  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