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24-Hour Urine Leucine-to-Creatinine Ratio

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

Measures urinary leucine relative to creatinine in a 24-hour urine collection to help evaluate how the kidneys handle amino acids.

Quick summary

["This test assesses how much leucine is lost in urine compared with creatinine, which helps evaluate amino acid handling by the kidneys."]

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

Key facts at a glance

LOINC
44334-1
Short code
Leucine/Creat 24h Ur
Synonyms
Leucine/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 leucine in urine relative to the amount of creatinine collected over 24 hours. Creatinine is used as a reference marker for urine concentration.

Why might I need this test?

Your clinician may order this test when symptoms suggest that the kidneys are not reabsorbing amino acids normally. It can also be used to follow certain metabolic or inherited conditions that affect nutrient handling.

How is the test performed?

You collect all urine for 24 hours in the container provided by the laboratory. The total volume and the amounts of leucine and creatinine are measured, and the leucine-to-creatinine ratio is calculated.

How do I prepare for the test?

Follow the laboratory's collection instructions, including when to begin and end the collection and whether to refrigerate the container. Record the total urine volume and avoid missing or spilling any urine during the collection period.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

A higher ratio may indicate increased loss of leucine in the urine, which can occur with impaired kidney handling of amino acids or certain inherited metabolic disorders. A lower result may reflect low intake, dilution, or reduced protein breakdown. Results should be interpreted with symptoms, diet, medications, and the other tests ordered by your clinician.

Short name

Urine Leucine/Creatinine Ratio

Frequently asked questions

Do I need to collect all urine for 24 hours?
Yes. This test is specifically based on a complete 24-hour urine collection, so missed urine can make the calculated ratio less reliable.
Why is creatinine included in the result?
Creatinine is used to compare leucine with a marker of urine output. This helps account for differences in urine concentration during the collection.
Does an abnormal result mean I have a kidney disease?
Not by itself. An abnormal ratio can have several causes, including kidney transport problems, inherited metabolic conditions, diet, or medication, so your clinician will interpret it with your full medical picture.
  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