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Leucine concentration in urine (24-hour collection)

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

This test measures the amount of the amino acid leucine found in your urine over a 24-hour period. Leucine is one of the building blocks of proteins and can be useful in assessing certain metabolic or kidney-related conditions.

Quick summary

["A 24-hour urine test for leucine helps doctors check how well your body breaks down proteins and if your kidneys are working properly."]

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

Key facts at a glance

LOINC
5798-4
Short code
Leucine Cry UrnS Ql Micro
Synonyms
Leucine Cry UrnS Ql Micro
Category
chemistry
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
microscopy-light
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

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if they suspect conditions like kidney disease, metabolic disorders, or protein loss in urine. It can also be part of evaluating conditions related to amino acid metabolism or muscle breakdown.

What to Expect Before the Test

You’ll need to collect all urine for a full 24-hour period, typically starting after you wake up in the morning and continuing until the next morning. Drink plenty of fluids but avoid foods high in protein (like red meat, dairy, or processed foods) unless instructed otherwise by your doctor.

How the Test Is Done

You’ll provide a 24-hour urine sample in a special container. The lab will analyze the sample to measure leucine levels. No special preparation is needed beyond following the collection instructions precisely.

What the Results Mean

Results are compared to a reference range that varies by lab, but elevated levels might suggest conditions like kidney disease or excessive protein breakdown, while lower levels could indicate malnutrition or certain metabolic issues.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Frequently asked questions

How long will I need to collect urine for this test?
You’ll need to collect all urine for a full 24-hour period, starting from the first urine after waking up one morning and continuing until the next morning’s urine. This ensures an accurate measurement of leucine over a full day.
Can I eat or drink anything special before this test?
Avoid high-protein foods unless your doctor specifies otherwise. Drink plenty of fluids to help with urine collection, but stick to standard dietary habits unless instructed to modify your diet.
What does a high or low leucine level mean?
High levels may suggest kidney issues, protein loss, or metabolic problems, while low levels could indicate malnutrition or certain metabolic deficiencies. Your doctor will discuss these findings with you based on your medical history and symptoms.
  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