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: Selenium [Mass Rate] in 24-Hour Urine

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

: This test measures how much selenium is excreted in the urine over a 24-hour collection period, which helps assess the body's selenium status and exposure.

Quick summary

[": A 24-hour urine selenium excretion rate reflects recent selenium intake and how well your body is handling this essential trace mineral."]

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

Key facts at a glance

LOINC
5727-3
Short code
Selenium 24h Ur-mRate
Synonyms
Selenium 24h Ur-mRate
Category
chemistry
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 Selenium?

: Selenium is an essential trace mineral that supports thyroid function, antioxidant defenses, and immune health. It is obtained mainly through diet from foods such as Brazil nuts, seafood, meat, and grains.

: Why Measure Selenium in Urine?

: Measuring selenium excreted in urine over 24 hours helps estimate how much selenium is being processed and eliminated by the body. It can reflect recent dietary intake and is sometimes used to evaluate overexposure or deficiency risk.

: How the 24-Hour Collection Works

: A 24-hour urine test requires collecting all urine produced over a full day, usually starting after the first morning void and ending with the first void of the next morning. Following collection instructions carefully is important because incomplete collection can affect results.

: What the Results May Indicate

: Results are interpreted alongside your diet, supplements, symptoms, and other tests. Values outside the expected range may suggest low intake, increased exposure, or differences in how your kidneys handle selenium, but they are not diagnostic on their own.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

: 24h Urine Selenium Excretion Rate

Frequently asked questions

: Do I need to change my diet before this test?
: Your healthcare provider may give specific instructions. Generally, avoid starting or changing selenium supplements before testing unless told otherwise, and follow any preparation guidance provided with your collection kit.
: What if I miss some urine during collection?
: If any urine is missed or not collected, tell your healthcare provider or laboratory, because an incomplete collection can make the results unreliable and may require repeating the test.
: Does a high result always mean selenium toxicity?
: No. A high urinary selenium level can reflect recent high intake or supplementation and does not by itself confirm toxicity. Your provider will interpret the result with your overall health picture and may recommend additional testing.
  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