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Serine-to-Creatinine Ratio, 24-Hour Urine

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

Measures serine and creatinine in urine collected for 24 hours and calculates their ratio, which can help account for differences in urine concentration.

Quick summary

["This test evaluates urinary serine relative to creatinine using a 24-hour urine collection."]

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

Key facts at a glance

LOINC
25980-4
Short code
Serine/Creat 24h Ur-sRto
Synonyms
Serine/Creat 24h 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 serine, an amino acid, and creatinine, a waste product used as a marker of urine concentration, in urine collected for 24 hours. The results are used to calculate a serine-to-creatinine ratio.

Why might I need this test?

A 24-hour urine collection can be used to assess how much serine your body is excreting. The ratio may help interpret serine levels when urine concentration or kidney function could affect the result.

How is the test performed?

You collect all urine produced during a full 24-hour period. The laboratory measures serine and creatinine in the collection and calculates their ratio.

How do I prepare for the test?

Follow your laboratory's collection instructions and record the start and end times. Collect every urine sample during that period, avoid overcollecting or missing samples, and ask the laboratory how the specimen should be stored.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

An abnormal ratio may indicate changes in urinary serine excretion, altered kidney function, or differences in urine concentration. Dietary intake, hydration, collection errors, medications, and metabolic conditions can also affect the results. Your clinician should interpret the ratio together with the individual serine and creatinine measurements and your medical history.

Short name

24-Hour Urine Serine/Creatinine Ratio

Frequently asked questions

Why is the result reported as a ratio?
The ratio compares serine with creatinine, which reflects urine concentration. This can make the serine result easier to interpret when urine concentration varies.
How do I collect a 24-hour urine sample?
Discard the urine produced at the start of the collection period, then collect all urine for exactly 24 hours, including the final sample at the end. Follow the laboratory's container, storage, and timing instructions.
What if part of the urine collection is missed?
Tell the laboratory, because a missed or extra sample can make the 24-hour result inaccurate. The collection may need to be repeated.
  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