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24-Hour Urine Selenium/Creatinine Ratio

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

Measures selenium excretion in urine collected over 24 hours, with creatinine used to adjust for urine concentration and collection completeness.

Quick summary

["This test can help assess selenium levels and identify possible excess or insufficient selenium exposure."]

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

Key facts at a glance

LOINC
29917-2
Short code
Selenium/Creat 24h Ur
Synonyms
Selenium/Creat 24h 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 the amount of selenium excreted in urine over a 24-hour period. Creatinine is also measured so the laboratory can adjust the selenium result for urine concentration and help evaluate whether the collection was complete.

Why might I need this test?

It may be used to assess selenium exposure, monitor selenium supplementation, or evaluate a possible imbalance. Your clinician may also request it when symptoms suggest too much or too little selenium.

How is the test performed?

You collect all urine for exactly 24 hours in the container provided by the laboratory. The urine is then analyzed for selenium and creatinine, and the results may be reported as a selenium-to-creatinine ratio.

How do I prepare for the test?

Follow the laboratory's collection instructions and record when you begin and end the 24-hour period. Tell your clinician about selenium-containing supplements, multivitamins, and any other supplements you take, because they can affect the result.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

24-Hour Urine Selenium

Frequently asked questions

Why is creatinine included in this urine test?
Creatinine helps account for variations in urine concentration and may help show whether the 24-hour collection was complete. It is used to adjust the selenium result rather than to diagnose kidney disease by itself.
Can selenium supplements change the result?
Yes. Selenium supplements, including multivitamins, can raise urinary selenium levels. Do not change prescribed supplements without discussing them with your clinician.
What if I miss part of the 24-hour urine collection?
An incomplete collection can make the result unreliable. Contact the laboratory or your clinician for guidance on whether the collection needs 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