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Phosphoserine/Creatinine Ratio, Urine

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

A specialized urine test that measures phosphoserine relative to creatinine. It may be used in the evaluation of certain inherited disorders of serine metabolism.

Quick summary

["This urine test measures phosphoserine normalized to creatinine to help evaluate possible amino acid metabolism disorders."]

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

Key facts at a glance

LOINC
13796-8
Short code
Phosphoserine/Creat Ur
Synonyms
Phosphoserine/Creat Ur
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 phosphoserine, a compound related to serine metabolism, in urine. The result is compared with the amount of creatinine in the same urine sample.

Why might I need this test?

It may be ordered to investigate unexplained developmental problems, seizures, or other symptoms that suggest an inherited metabolic condition. It is typically interpreted by a specialist along with other laboratory and genetic findings.

How is the test performed?

A urine sample is collected and analyzed in a laboratory. Creatinine is measured at the same time so the phosphoserine result can be adjusted for how concentrated or dilute the urine is.

How do I prepare for the test?

Follow the collection instructions provided by your healthcare professional, including whether a first-morning or timed urine sample is required. Do not restrict food, fluids, supplements, or medications unless your clinician specifically instructs you to do so.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Urinary phosphoserine ratio

Frequently asked questions

What does the creatinine adjustment mean?
Creatinine is used as a reference marker for urine concentration. Reporting phosphoserine relative to creatinine helps reduce the effect of variation in how concentrated or dilute the urine sample is.
Is this the same as a routine urine protein test?
No. This is a specialized metabolic test for phosphoserine, while routine urine protein tests look for protein or albumin in the urine.
Does an abnormal result confirm a genetic disorder?
No. An abnormal result may guide further evaluation, but a diagnosis usually requires additional laboratory testing, genetic testing, and assessment by a metabolic specialist.
  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